As a 65 yr old fitness neophyte, so do I.
Good food, a little too much sleep and more exercise than you think you “ought to be doing” is the recipe.
No less than 150mins of low intensity cardio per week, with one HIIT session and a little weight training. Or, a lot.
Depending on what your joints can handle.
But still, more than the average person thinks they ought to be doing for “over 60”.
I work mainly with people 40 and older. Your prescription is a very good one. I have my clients use a rating of perceived exertion for intervals three days a week, with lesser cardio sessions the remaining days of the week. As their V02 max improves, I shift them to heart range levels three days a week, starting at a 1 minute up, three minutes rest ratio, graduating to an ultimate 1:1 ratio. I am a NASM trainer and was ACE for ten years.