By running "downwards" do you mean running south in a top-down world? Your sprite is side view rather than any sort of top-down, so running south doesn't really make sense without a major perspective overhaul. That's probably why you're struggling. If you redrew the character to face forward, you could draw them running towards the viewer, but not down.
There's no way to just modify a side-facing sprite into a front-facing one. You could use it as a proportion/feature guide, but you'd need to redraw just about everything, because most things look different when viewed from a different angle.