I also wanted to add that Ive had training friends and coleugues over the years who have used their age as an excuse for laziness, almost talked themselves into it.
What older people including myself forget is that hard training can be painful at any age.
We recently had a 23 year old fitness instructor join my little martial arts group and it was interesting to find that he was complaining of being sore and tired the next day, the difference between him and the older guys was that we get depressed and say "Im too old for this"
Life is short. There will be plenty of time to rest when its over.
You might feel like **** after some hard training, dont let it put you off.
The alternative is a slow motion deterioration of health.
yes get a medical clearance first, but never let age be an excuse, it will ruin your health.