Intrinsic vs extrinsic motivation. A related quote from management guru Peter Drucker goes something like: don’t hire people and motivate them; hire motivated people.
There have been studies. Intrinsic motivation is always better. That said, if intrinsic is missing, for extrinsic, they say rewards should come often and timely. Eg, giving $100 for passing a midterm is not as effective as $10 for passing the weekly quiz.
To help myself accomplish tasks I’m not interested in, I leverage the rule of threes. I set 1-3 accomplishable tasks for a time period (say before lunch). Instead of “rebuild a deck,” I have much more fine grained milestones: tear out the old deck, take old debris to landfill, level the ground, place footings... The reward is moving onto the next task. By limiting how many projects I have, I don’t get to start a new one until I get something else “done enough.”
Some examples I’ve heard from others where external rewards helped: someone would buy the next $item in $set (game pieces for a table top game, or car part for a restore, or anything that let them do more with a hobby), would add $funds to $project (dollar in the music instrument fund, n minutes of video games, time to decompress), and my favorite, they would do something nice for someone (write a quick love note, or let someone know you appreciate them and why, a small compliment; give themselves the joy of helping others).