I look at pictures of hot chicks on tumblr. Quite a few times, that has actually motivated me to work out when I was about to skip. I find the quotes that accompany them to be too soft though...."no matter how slow you run, you're still lapping everyone on the couch" etc
Actually that is a pretty good quote. But I find things like, "stop being a little bitch who lacks discipline" to be more motivating

Can't really find that on tumblr.