I was in great shape after my mission. After a lot of health issues and other circumstances I weighed close to 100lbs more than when I was married in less than 4 years. To top it off, I lost a ton of muscle and made up for it and more in just fat.
I tried every now and then to diet and work out, but every time I hit the gym or went running I ended up getting discouraged because every notch on my belt or weight I tried to lift or mile I tried to run reminded me of just how out of shape I was and how impossible it seemed to get back to that ideal I set for myself.
Over the past little while I changed my perspective on what my ideal was (still keeping health in mind) and have been doing a different program. I have lost weight and gained muscle and confidence as I try something new and try to be a different shape than I was a little while ago and different than my original ideal. That has energized me and kept me on track. Instead of shame I feel accomplishment as I try new exercises to reach different goals in strength and endurance than I did when I thought I was in great shape. I'm getting into great shape, just focusing on different goals and that has made all the difference for me.