You can make exercise a habit by going easy on your mission to get going at it. The harder you go on yourself, the more likely it is for you to feel burnout. The best way is to start slowly and gradually maintaining consistency and then moving on to increasing the intensity and time of your exercise. Also, look for friends who can tag along with you on exercise sessions to make it a fun experience, you can also download apps like Pokémon go which can motivate you to go out and have fun.