That Murph sounds like a tough workout. I ran my last race 7 years ago when I turned 60 and that was a 10K. What started getting to me was it takes longer to recover from those intense workouts as I got older. But when I was running 70 - 100 miles a week I could not gain weight. I still miss the running and keep saying to myself "I am going to start again" but that hasn't happened. I do try to keep active by hiking every day of the week, lifting weights and splitting as much wood as I can by hand. I know I am carrying a few pounds but my weight has been stable and my BMI is still under 25. Trying to eat more protein and less carbs, and instead of beer I drink red wine. Figure that also counts as a fruit serving. I don't like desserts so that keeps me away from the extra sugar. It really comes down to one thing - keep moving.