It'll take time and work but you can get back to where you were. Eat healthy and get some exercises. I'm 58 and it's impossible to be like you're 20 but in the almost one year sober I've lost 50 lbs, went from only being able to do a 15 walk to trekking to Mt Everest base camp this May and doing bike rides of up to 4 hours, 65 miles this summer. It was concentrated effort but I'm in as good a shape as I was in my 20's and look a Heck of a lot better than I did a year ago.