Age is an excuse.
I attend exercise classes with age ranges from 20s to 60s. Age does not seem to be an indication of who will push themselves harder or turn up more often.
I’m 60 this year and I go to the gym 4/5 times a week, I’ve tried to keep fit , all my life, in fact it’s saved my life a few times , I never thought at 50 years of age , well time to stop , in fact I never thought about my age , just carried on with what I had been doing most of my life
I do exercises almost every day. I make sure to watch my heart rate. I found a good training program on this site https://www.seniorfitness.net/ There are lots of other useful information about fitness.