Don't think I hit euphoria that often but I'm certainly in a far better frame of mind when I cycle to work rather than catching the bus/train. There's always at least one moment on the bike commute where I find myself breaking into a big smile and feeling a little like an 8-year old again.

I do still go to the gym (for resistance and more interval cardio classes) but can now happily skip the spin classes and go fewer times a week.

I used to look and wonder at the mentality of some of the cyclist commuters in the office but am now truly converted. The roads really aren't as scary as you think (particularly after some excellent Bikeability training - free/subsidised by councils) and it doesn't rain all that much either. I've been drenched only 2/3 times in 20 months of commuting (in the summer so didn't really matter) and got the wet weather gear (trousers/jacket) out 3-4 times too.