At 75, I use Cronometer.com to track what I put into my body and exercise which is quite illuminating. Highly suggest using some sort of program or app to track calories, carbs etal with exercise burned kcal. Tends to keep you on track (pun). 😉
I walk 2.5 miles to 5 miles a day, use kettle bells at home and an old NordicTrack more during the winter. Always walk usually with Minimalist set of 5-8 clubs when playing golf helps a lot. I still work on clubs and also a 3 hour part-time job weekday mornings May to October to stay active. Bowl 3-4 leagues a week during fall/winter.
Stay away from sugar, chips and dip, donuts etc. I know it's not living the high life but I feel pretty good and better than most in my peer group of same age range. Never had a joint knee/hip replacement and can keep up with any golfer I walk with and most are much younger. It helps to stay out of the recliner. ☺