Reward yourself for good habits

I don't always feel like going to the gym, yet I've made it a habit to go three times a week anyway.

Well, until the spread of COVID-19 forced the government to close all gyms. But that's besides the point.

The point is: how did I develop this habit despite feeling some resistance? By adding a reward.

I like to listen to podcasts, such as Hardcore History, Pod Save America, and Climate One. But listening to podcasts takes time and, while it is entertaining, doesn't contribute much to my long-term happiness. So I don't like to just sit around and listen.

Instead, I listen to podcasts on the way to the gym and on the way home. It's 50 minutes of travel time each time; three times a week, that's a lot of listening time. It makes me feel like going to the gym even when I'm tired or haven't slept well.

What's a positive habit you want to build—and how can you combine it with a reward so you're more likely to do it?