Man yer a youngster! I'm 48 yrs. old and have had five (two major) knee surgeries alone, injured a lot of other stuff too. Still going strong. It can be done. Knees are easy compared to backs and shoulders! Still beating college kids on the 10-S court with virtually NO cartilage in either knee. NO ACL in left knee, partial tear of MCL in right. I don't wear a knee brace anymore either, agree with Rick that's only for rehab and becomes a crutch and leads to atrophy after that (tho i will put it on if i'm tired and want to ski more). Bottom line - there are three or four things that will determine your ability to continue:
1 - Attitude (STAY POSITIVE Remember, almost all of the recent great alpine ski champions - Phil Mahre, Stefan Eberharter, Herman Maier and Bode Miller, et al. all had MAJOR knee/ankle/leg surgery before winning the world cup overall!!!)
2 - work ethic with rehab (GOTTA PAY YER DUES)
3 - quality medical care (ALWAYS get a FEW opinions before letting anyone cut on you or before giving up if not better w/o surgery)
4 - your own physiology (the human body, particularly the male body, has an amazing ability to repair/adjust itself, but everyone's knees are different)
5 - your own pain tolerance (you can/will learn to ignore the dull aching, throbbing, non-piercing pain that comes with mileage)
6 - Learning to accept some limits (I certainly agree the worst thing you can do is push it and rush back. Not only can you re-injure the old injury but favoring one side can lead to host of other problems. Also, gotta watch those downhills. Use poles and wrap your knees before any major downhills.)
You'll be fine, just have patience, do yer own research - and don't be afraid to question yer doc and get a second/third opinion.