Get moving, even if it's a small thing. Clean your room, take a shower, whatever you do, DON'T STAY STILL. Avoid the internet if its causing you distractions.
And whatever you do, do NOT stew. You have to flirt with productivity by accomplishing small tasks, eventually you'll start to feel better and get more ambitious, then inspiration will eventually strike and you'll feel a lot more alive.
But you've just got to keep moving to build that momentum. If you feel small and too weak, that's okay, just start small and little, and be patient with yourself. You're not going to finish everything at once, what matters is that you KEEP ON THE MOVE.
So if you're on the internet now, and not moving, get off and start moving, beware of distractions, take care of yourself be it hygiene or cooking a good meal, etc. These things will dovetail into bigger tasks and ambitions with time, so just keep your eyes ahead of you. Don't dwell on failures, don't stew, if you're stewing in bad thoughts, take a shower, take a walk, just don't do it by finding something to do.