51 y.o. and still trying

I was a runner for many years (50 mi. per wk)then the knees went. I sat around for the last 5 years putting on 50 lbs. Since 01/03 I have lost 30 lbs. while packing on some muscle. I watch what I eat, but don't diet. I use light weights 3 times a week. I took up biking about 2 months ago and average 20 miles per ride twice a week. I recently got the bug to get in shape for a mini Tri. Surprisingly, my knees do not appear to have a problem with running again but the lungs do. I think the bike has helped a lot. Swimming is another challenge, but that too shall come. So, I'm glad to be off my fat butt and back amongst the living.