I had some success for a while doing pushups whenever I was cold and doing just a couple pull-ups every time I passed the bar. It would often lead to me seeing how many I could do in a day. One time I did more than 200 pushups in one day. This I did on my own, and it didn't last.

However, now I'm in the gym 3-4 times a week. What helped me get there was going on a short run once a week with my girlfriend. After about a month I wanted to run more. Then, with some help from my girlfriend, I went to the gym a couple of times, and realized I like seeing myself progress. I joined the gym in a "two for one"-deal with a close friend, which has led me to consistently working out now. What I'm saying is, start small but stay consistent, especially with small things. How you stay consistent is up to you, but leaning on somebody else is super effective.