My "Did it" list
Having knocked off a few things from my to do list, I often find I get other things done, too. Maybe they were from "to do" lists of yore, things I'd forgotten. Or as often something new that just came up, and since I was already in "doing" mode, they got done.
So I add those to the list, then I get to cross them off! Every item I get to check off helps with that feeling of being productive.
There are many areas where this approach works, not least of all writing and riding (I love the phonics of those two words together!). If you aren't riding, you and your horse won't improve, get fitter, gain strength, bond, or even enjoy each other – insert your goal here – and take one step toward achieving it.
If you are staring down at a blank page, despite the brilliant idea in your head screaming to get out, just write anything! A few key words or phrases you're afraid you'll lose on the topic. Or, start a new piece unit the old one just creeps in because it needs to get written. Heck, sometimes just rewriting my "to do" list gets me going (and sometimes not).