In the past five years, I've done about 1,750 trips to and from the office. It's a roughly 10km trip, which means I've put 17,500km on the three bikes I've ridden in that time. Each trip takes me about 30 minutes, so that's 875 hours, or well over forty weeks on the bike. I bet that's been good for my fitness; I know that when I had a heart stress test, the doctor told me that my heart was in better shape than his.
And that's just commuting. While my cycling for errands and recreation was likely much less, it's also not nothing. I'd expect it would add another 2,500km at least, putting me in the 20,000km range just this past five years.
I've also saved about $4,700 in TTC fares, by my records.
But more than that: I've spent all that time free of cars and transit, free to go where I please and stop where and when I've liked; I've taught my son to ride with confidence in the city; and I've gotten to know the city better than I would sealed up in a car. Hooray!