I want to start commuting to work via bicycle. My work place is about 15 miles away. I have already done it twice but I want to make it a more regular thing to save on extortionate driving costs. The thing is my job involves walking long distances while moving heavy goods around all day. I also have to regularly bend my knees and climb stairs. Basically I'm exerting my legs non stop (except for breaks obviously) all day until I get home. Will doing this 4 or 5 days per week have some sort of detrimental effect on my knees? Inevitably I will suffer fatigue at some point but I mean is there potential to damage any joints through over use? Im aware some people cycle or commute great distances and seem to be fine.