I tend to think to myself "I'm bored" a lot, so I've decided every time I get bored I am going to make myself do 10 push ups. I will either stop getting bored real fast or get a massive chest.... Lol
If you're bored for a period of time Id go ahead and go to the gym. That's what I do. By the way, no amount of pushups will add any considerable size to your chest.
I actually used to go to the gym 5 days a week.... And then I had a kid and all my free time went out the door