Try cardio outside. Pick a route of the length you want to run and run it. Running in a gym constantly requires willpower to go on, especially when you're getting tired. Running outside only requires to start, but when you're getting tired you are away from your house so you don't really have a choice. Also: fresh air, better temperatures, quiet and better scenery.

I run several times a week and it requires almost no willpower, whereas I would definitely not have the willpower to run for an hour on a treadmill even once.