[Reiver]

Kachi...just saw this thread...good for you.
I'm 5'9", 65, 172 lbs and have worked out all of my life (part of my job).
On the elbow....never over extend on repetitive exercises, this is especially important as you age.
Often, with lighter weights, folks increase speed with the reps and overextend the ligaments....don't do it.
Drink a good whey protein after you work out.
Pro tip I got some years ago when doing weights.....15 second interval between reps/exercises.
You work up a blood/muscle pump...then most rest too long allowing you to lose the pump.
It takes practice to get organized but I do that and time it...you will feel it.

For the older folks like myself....you need to do muscle building exercise not just aerobic stuff.
How many fat walkers do you see? You were designed to 'walk'....unless you are walking 10-15 miles at a brisk pace carrying a load it's not much of a work out.
Muscle burns fat and older folks stop building muscle and complain that their aerobic work out isn't slimming them.
Good aerobic is serious cycling, swimming, rowing....hard. Walking, by itself, yeah if you are sick or crippled.
I suspect you have multiple strength work outs you do on alternate days.
Nothing wrong with your weights....never quit. I've a friend in his 70's still running marathons...fast marathons. He lifts too. You need both.