I found exercising on my own and working too hard so took out membership of a gym. It doesn’t cost me much per week but paying in advance helped me get into the gym habit. Now it’s automatic. Establishing good habits takes longer than starting bad ones! I agree there are no easy answers for diet - we all know what’s bad for us. Rewards however can be insidious - reward for having a bad day, reward for being good, reward for almost anything. I found trying to reduce the things that ‘deserved’ rewards helped, but still a work in progress. Best wishes.