It can be very difficult to start new things while at a low point. Of course, sleep and exercise are definitely helpful, however they may not be the solution all the time. I'm curious if you are trying to do too much when you are motivated, especially as you may go through periods of putting things off. If this is the case it might be beneficial to work through with your future professionals in relation to breaking down your tasks into small, doable ones, so over time you can see progress and they are not overwhelming in the moment. This is very hard to work out over the forum without doing some sort of assessment with you or working through you progress periodically.
Working with a regular professional who can work with you through your goals may be a helpful step to take, which it sounds like you are in the process of doing. If you don't have a psychologist or professional that is helpful from the start, we would suggest to keep looking for a professional who is a good fit. Rapport can be a major factor of progress. Hopefully this is helpful information for you.