I have been making a very strong effort to do some type of exercise for at least 30 min every single day. I've been doing this for long enough now to really feel the difference between when I'm on it, and when I've slacked off for a few days. My go-to exercise is walking. I love walking, and it isn't too strenuous so I won't try to avoid doing it.
One other habit I've developed, sort of accidentally, but it's working so I'm going with it, is that I save my audiobook listening time for my walks. Now I've made it a rule. I can only listen to my book when I'm walking. Now I enjoy walking enough that this rule has never gotten me out walking when I otherwise would have shirked. It has, however, encouraged me to take a longer route, or keep going around the block one more time if I'm at an exciting spot in the story and don't want to stop yet.
I'm currently on book three of the first Mistborn trilogy by Brandon Sanderson. These are big books so even with hour long walks these have lasted me a nice long while. The narrator, Michael Kramer, is amazing. There's a large group of characters and they all have a distinct voice that adds to their personality. I highly recommend the book, or the audiobook if you want to try the walking thing.
Now my only problem is that now I'm doing the Couch to 5K running program three days a week, and I've learned I don't listen well while trying to run. So I really miss my story on running days. I'm debating about changing my rule to compensate for this somehow. Still thinking.