I've been at this fitness/ weight loss thing for a couple of weeks now. This year I've basically been in front of the computer at home all day, not really leaving the house, because of unemployment/ health issues.
When I first started going on the walking machine I could only do 10 minutes at a time at 4km/hr, stopping for a lie down each time. The only way I could do more was to bandage up my knees, walking on soft grass on the oval, as my knees were so sore. I thought I had arthritis, and I'm only 32!
Now I can walk up inclines on the walking machine, from 4-5km an hour, for over 60 minutes at once! With no knee bandages!
All with just 2 weeks of consistent effort.
It must have been weak muscles in the legs that were causing the knee pain...