I think the most important thing that you can do is find a way to really enjoy exercise, if it is a chore or something you hate doing I can guarantee you won't be making any gains. Look at any great bodybuilder/powerlifter and you will see that they love fitness, you aren't going to find anyone who is in great shape and doesn't enjoy working out.

There is a lot of ways to work out, so if commitment is ending up being your problem try changing it up, weight lifting doesn't work out for you? Try bodyweight? Try joining a local sports team if bodyweight isn't your thing.

All I can say is that if every time you go to workout you are filled with remorse, you will quit . Working out needs to be something you like to do. If it is something your brain associates with negative feelings its not going to be good for you to keep doing, and your gains will be severely damaged.