Had cartilage replaced, back when having it replaced was a new surgery. Had two surgeries and now I have someone else's cartilage in my knee. Lost a lot of spring, and ten years later it feels closer to normal after I started building strength back into the leg. On cold days, or days it generally just feels weak, I swear I can feel that little piece in my knee.
Hardest part, was going from always being active, to constantly limping, then having surgery and not being able to walk without assistance for six months, and then not being able to do more than walk for rest of the year (it's now a shorter process). I took it pretty bad, but I was also dealing with other things.
Highly suggest getting a hobby. Don't know what recovery/rehab takes for torn ACL, but definitely find something to do off board. Don't get comfortable with those pain pills they give you. Stay away from the alcoholic beverages, as it affects recovery/ rehab.