Psych Yourself Up!:
Pretend you're a boxer, a marathon runner, a professional athlete, be a fast running gazelle... it sounds corny, but it works. Get yourself in that mindset, be the boxer, get yourself pumped up, channel Rocky if you want. See it, feel it, see the environment you would be in. The point is to get your head in the game and out of your "I don't feel like working out" head.