I haven't gotten that far. For me it's the threat of death from my wife. I've started mostly on cardiovascular exercise and have lost weight. At the same time I have lost a lot of muscle. Muscle is lost whenever weight is lost, but one way to lose LESS is to do weights along with your aerobic exercise.
Support is important and sometimes motivating.
She already has one. She wants me to do it with her. I just have no desire. The risk of a fatal heart attack is twice as likely among sedentary individuals than among active. That does put things into perspective.