Exercise even if you only have 15 minutes to do it. A short gym routine is better than nothing if you're really strapped for time or just plain exhausted. If you don't have time to get to your gym but have 15 minutes before you have to shower to go meet your friends for dinner, do jumping jacks to Taylor Swift or something. 

You'll feel better, especially if you spent your day sitting at a computer listening to Taylor Swift and thinking about how you should really leave work in time to get to the gym. (But then, well, didn't.) The worst. Usually, working out just to avoid the feeling of sitting around in gym clothes watching Bravo and eating snacks and never actually going for your run is worth it. Read more here: