Older body here, and I have real trouble with over training due to impaired muscular function and recovery. The only way I can work out regularly is with rest days at least every other day. So work out MWF, walk 2-3 miles every day.
Monday and Friday 1 1/2 mile walk, thera/stretchy bands and a few assisted sets of knee pushups, pullups, light dumbell work to warm up. Then full body exercises, I don't do isolation work. Pull ups with knee/leg lifts, several types of push ups, (It's been a while but when I can I add weight to these body weight calisthenics) and compound lifts with barbell and dumbbells like squat with curl, clean and jerk, snatch, though form somewhat adapted for smoother more continuous motions to reduce spine compression (recommended by my PT). I shoot for one set each with weight for around 10 reps then up weight for two more sets 5-7 reps to failure. So overall workout time is short sweet and comprehensive throughout the body
Wednesday, HIIT, warm up with 1.5 mile walk, then usually about 4-6 intervals sprinting up hill intensely and long enough to leave me unable to run further, heaving/gasping for air. Continue walking for 1-2 more miles.
Recreationally, I have been rock climbing for close to 40 years, and climb at a high level for my age. Physical enough that I require 1-2 days rest after climbing days. Rock climbing days substitute for workout days.
Minimum of 30 minutes of stretching every evening, primarily for back, hips, legs,