If you have faith in your surgeon, accept the risks, get a little good luck & are dedicated to your rehab Life will more than likely be good.
Without surgery, the tear could lodge and lock the knee at the most un-opportune time causing more damage possibly. It can happen stepping off a curb.
My medial meniscus was torn (as a young teen) opted for no surgery & did exactly what I described above. Tore my MCL, ACL and totally ripped to shreds my remaining mensicus so the doctor removed it
Fast forward through the years, more surgeries, lots of pain, not good!
I had my knee totally replaced on June 14th 2010! It is awesome!
Yes I have to go to the gym and keep my muscles strong especially if you like to hike, ski, bike & be active like I do. As far as cutting sports, volleyball, raquetball, I made different choices. Its a point where I like doing other things now, but that is just me.
I guess my point is I wish you the best of luck in whatever you decide. I know it stinks, knee injuries are really depressing especially if you like to be active. Stay strong and come here and vent. There are many of us who have had it done and made through the other side.