This has been my biggest struggle with health. I've always had troubles with autobiographical memory and without it, I can't stay motivated because I quickly forget how good exercise felt or how junk food made me feel a few hours later. I started going to the gym to dogfood when I joined a fitness company and within a few months I was looking a lot better but not feeling it. It wasn't until I started to really push my limit with rowing workouts that I felt the "runner's high" athletes talk about. From that point on, it was felt like I was discovering a new muscle group every few weeks and correlating how far I rowed in a 60 minute rowing session with my diet and lifestyle. Junk food that I would scarf down because unappetizing. Drinking alcohol went from a no-brainer to "how will I feel tomorrow?" Morning stretches and exercise became mandatory just to feel "normal."
Even now, with the gyms closed for months, I can feel that newly acquired skill slipping and predictably, my self discipline slides too. I've almost forgotten how good it feels after a nice workout.