Do you use any support gear? Like elbow or knee sleeves? Get regular (at least once a month) sports massage or osteopathic treatment. And also look at a solid joint product (at the very least Glucosomine at 1500mg a day) and fish oils (2000mg).
If you look at my log you'll see I do exactly that kind of volume. In fact, right now, often lower.
The age thing is kinda BS. My most recent training partner on bench day is 77. We train to stay young. Another gym buddy is also 77.
And the 'I don't wanna do heavy squats'.... c'mon. By all means alternate machines with free weights but do NOT drop stuff cos it's hard. And I DO use support gear. By way of example (again in my log) I literally just gave Cerebus Extreme (their stiffest) knee wraps a go yesterday and did 270kg squats (4 reps) and 750kg leg press (3 reps - bit too heavy). It is, of course, relative. Heavy for you vs heavy for me. Support gear is only worn on the heaviest sets.
In order to cause growth, add strength and or lose fat you gotta 'go hard'. Easy would be staying at home.