It hurts. That heavy, sinking feeling in the chest when you realize you're still obsessing over a person, a job, or a version of yourself that doesn't exist anymore is exhausting. You want to move on. Everyone tells you to "just get over it," as if you haven't already tried that a thousand times. But your brain won't cooperate. Honestly, there is a biological reason why you can't let go, and it has almost nothing to do with your willpower.
Brains are stubborn. They are wired for survival, not necessarily for your personal happiness. When we form deep attachments, our neural pathways literally reshape themselves around that person or situation. It becomes a physiological habit.
Breaking that habit isn't just about "thinking positive thoughts" or deleting a few photos from your phone. It is a grueling process of rewiring your internal chemistry.
The Dopamine Trap: Why the Past Feels Like a Drug
Think about the last time you checked an ex's Instagram or re-read an old, angry email from a former boss. You probably felt a rush of something—maybe anxiety, maybe a weird flick of nostalgia. That’s dopamine. Even if the memory is painful, the "hit" of familiarity is addictive.
Dr. Helen Fisher, a biological anthropologist who has spent decades studying the brain in love, found that being rejected or stuck in a cycle where you can't let go activates the same regions of the brain as physical pain and cocaine addiction. Specifically, the ventral tegmental area. This part of your brain doesn't care that the relationship was toxic. It just wants the reward it used to get.
You're basically a lab rat pressing a lever that no longer gives treats. You keep pressing it because the memory of the treat is more powerful than the reality of the empty tray. This is what psychologists call "intermittent reinforcement." Since the "reward" (the good times) happened unpredictably in the past, your brain stays on high alert, hoping for one more hit. It’s a vicious cycle.
Rumination is a Survival Mechanism Gone Wrong
Why do we replay the same scenarios?
"I should have said this."
"If only I had done that."
💡 You might also like: How to Treat Uneven Skin Tone Without Wasting a Fortune on TikTok Trends
This is rumination. It’s your prefrontal cortex trying to "solve" a problem that has no solution. In the wild, if a predator attacked you and you survived, your brain would replay the event to make sure it never happened again. But in a breakup or a career failure, there is no predator to outrun. The "threat" is internal.
By replaying the tape, your brain thinks it's doing work. It feels like progress, but it’s actually just digging the groove deeper. The more you think about why you can't let go, the more you strengthen the neural "roads" leading back to that pain.
The Zeigarnik Effect and Unfinished Business
Blame Bluma Zeigarnik. She was a Soviet psychologist who noticed that waiters remembered orders that hadn't been paid for much better than orders that were already settled. We are biologically programmed to remember incomplete tasks.
If a relationship ended without "closure"—a word that is mostly a myth anyway—your brain views it as an open file. It stays "active" in your mental RAM, sucking up energy. You feel like you can't let go because your mind is waiting for the final chapter that never got written.
Realities of Closure
- Closure is something you trade for peace.
- Waiting for someone else to explain their actions gives them power over your timeline.
- Most people don't actually know why they did what they did.
- The "explanation" you're looking for probably wouldn't make you feel better anyway.
The Role of Cortisol and the "Heartbreak Heart"
It’s not just in your head. It is in your blood. When you are stuck in a state of chronic longing or regret, your body is flooded with cortisol and adrenaline. This is the "fight or flight" response, but it’s stuck in the 'on' position.
Long-term exposure to these hormones causes physical exhaustion, a weakened immune system, and even "Broken Heart Syndrome" (Takotsubo cardiomyopathy). This isn't just poetry. It’s a clinical condition where the left ventricle of the heart changes shape due to extreme emotional stress.
If you feel like your body is failing you while you're trying to move on, it’s because it kind of is. You are physically ill from the stress of holding on to something that is gone.
📖 Related: My eye keeps twitching for days: When to ignore it and when to actually worry
Cognitive Dissonance: The Two Versions of the Truth
One of the biggest hurdles is the gap between what you know and what you feel. You know they were bad for you. You know the job was soul-crushing. Yet, you still miss it.
This is cognitive dissonance. To resolve the discomfort of holding two opposing ideas, your brain often "filters" the bad memories. This is known as rosy retrospection. You remember the one time they bought you flowers but forget the three months they ignored your texts.
You aren't missing the reality. You are missing a curated highlight reel.
Steps to Rewire the Brain
If you really want to stop feeling like you can't let go, you have to treat it like a physical injury. You wouldn't run a marathon on a broken leg. You shouldn't expect your brain to "just be fine" without a structured recovery.
1. Radical Acceptance (The "It Is What It Is" Method)
Stop fighting the reality. Acceptance doesn't mean you like what happened. It just means you stop protesting that it happened. This lowers the cortisol levels because the "fight" is finally over.
2. Interrupt the Loop
When a ruminative thought starts, physically move. Stand up. Splash cold water on your face. This engages the "mammalian dive reflex," which forces your heart rate down and snaps your brain out of its circular thinking. It’s a circuit breaker for your mind.
3. Inventory the Bad
Write down everything that was terrible about the situation. Every mean comment, every late night crying, every moment of disrespect. When your brain tries to show you the "highlight reel," force it to read the "blooper reel." This counters the rosy retrospection and brings you back to reality.
👉 See also: Ingestion of hydrogen peroxide: Why a common household hack is actually dangerous
4. Create New Neural Pathways
The "letting go" part is actually just "filling up" your life with something else. Start a hobby that requires high focus—something like rock climbing, learning a language, or even complex video games. These activities force your brain to use the resources it was previously using to obsess.
The Myth of the Timeline
There is no "magic date" where you'll suddenly be fine. Some people take three months; some take three years. The pressure to "be over it by now" actually makes the process longer because it adds a layer of shame to the existing pain. Shame is a "sticky" emotion—it keeps you tethered to the past.
Understand that healing is not linear. You will have weeks where you feel great, followed by a Tuesday where you see a specific brand of cereal in the grocery store and suddenly feel like you're back at square one. That’s not a relapse. That’s just how the brain processes data.
Actionable Next Steps
Start by auditing your digital environment. The brain cannot heal in the same environment that made it sick. If you are constantly "checking" on the thing you're trying to leave behind, you are effectively reopening a wound every time it starts to scab.
Immediate actions to take:
- Go "Dark" on Social Media: You don't have to delete your accounts, but you must remove the ability to "lurk." Muting isn't enough; sometimes blocking is a necessary act of self-preservation.
- The 90-Second Rule: When a wave of sadness hits, sit with it for exactly 90 seconds. Research by neuroanatomist Dr. Jill Bolte Taylor suggests that the chemical component of an emotion only lasts about 90 seconds. Anything after that is you "stoking the fire" with your thoughts.
- Physical Displacement: Move your furniture. Change your scent. Buy new sheets. Give your brain new sensory input so it stops associating your physical space with the person or event you're trying to leave behind.
- Focus on the "Next Small Thing": Don't worry about where you'll be in a year. Focus on the next 15 minutes. What is one thing you can do right now that serves your future self? Drink a glass of water. Fold one shirt. Just one.
Letting go is a quiet, boring, and often frustrating process of choosing the present over the past, one tiny second at a time. It’s not a grand gesture. It’s a thousand small decisions to stop looking back.