Post Exertional Malaise removes your ability to make the choice to physically move.
All these things can cause stress which has also been shown to affect your decision-making skills
So am I saying that people should just up and give up on trying to control their own choices? Oh my goodness no! Instead, I think a much more effective way to handle self-improvement is to focus on your habits instead with judging them.
I highly recommend the book: 'The Power of Habit' by Charles Duhigg
Although my critique might seem like splitting hairs there is actually a huge difference between focusing on your 'choices' compared to focusing on your 'habits'. Focusing on habits allows you to make S.M.A.R.T goals (Specific, Measurable, Achievable, Relevant, Time-bound) while focusing on every single choice you make in a day is both frustrating and mentally exhausting.