The language-learning case is an interesting example. There are some things you can do.

One is that, if you're extraverted, instead of studying Swahili by hunching over books of grammar, you can study Swahili by talking to cute Kenyan exchange students. This way, the actual process of learning itself is enjoyable. (Mostly. You'll still be embarrassed frequently, and it's in your interest to turn the embarrassment dial up further by asking them to correct your grammatical errors.)

Another is that you actually can make the decision to study Swahili "in aggregate," rather than every night. Just go to rural Tanzania for six months and don't take any books or English-speaking friends with you, keep your internet access to a minimum.

This strategy has worked reasonably well for me in learning Spanish, although my Spanish is still pretty unidiomatic. I still speak English often with my wife, and I work online.

To generalize the principles a bit, if you can find a fun way to achieve your approved-of goal, a way that you enjoy, you're more likely to do it; and if you can find a way to make the decision once instead of numerous times, you're more likely to do it.