I had my right knee done 2 years ago. The first 2 weeks were very painful, but things started to improve after that. It does ache once in awhile, but that is just muscle ache - I think. Need to have the left knee done now - have to prepare myself. I know people that have had both knees done at the same time - I consider them heros!!! I think one reason they do not want perple jogging, skiing, etc is that the replacement parts will wear out sooner, but while I was in the hospital one of my nurses (with knee replacement)would run up and down the hall and I mean RUN. Just remember to do your exercises and PT. And don't forget to take the pain pills!!!!
Good luck! 27 is young, but for her not to be in pain will improve her life so much!