20 September, 2019 - 02:49 AM
Sometimes a lack of motivation is simply telling you that you're not interested in doing something and you should find something else to do. In your case you mention excercising while already being skinny. I think this is just a lack of interest and nothing more, you probably just don't see the need in having defined muscles as you're perfectly happy with the way you look already. Maybe you just haven't found what interests you yet. Keep looking :D