It will never end from co-workers and complete strangers. However the family and friends will quiet down after (1) you lose the spare tire around your midsection, (2) your grouchy self after a car commute turns into a a good natured self after a bike commute, or (3) you make it through the winter bike commuting even as little as 3 days per week. Just get on the bike in the winter at least twice a week and the comments will taper off right quick. Stick with it and by this time next year they'll have stopped.

Once people who love you see that you are doing something good for yourself they will support you. They just have to have the goodness smashed against their face repeatedly before they see it.