Give more of my will power to myself or to someone else? Seems to be an easy answer.
It's also instrinsic motivation when you work on side projects. That is definitely harder to push after a full day at work.
At work, the motivating factors are different, and you have someone pushing you to get stuff done.
Sure, if the things you're doing before work require willpower to pursue. They don't have to be. And jriot's point in my sibling comment is in any case well made.
I do this and just front load my day to have the more demanding stuff in the morning with the less demanding in the afternoon. It works well for me and if anything I feel my productivity has increased.