I don't think lycanthropy in D&D changes the lifespan of the creature afflicted with it (at least, I can't remember ever seeing something which says it does).
Of course, since a DM can always deviate from whatever the books might say, it's best to ask your DM (or rule with what you think sounds cool if you are the DM).
I know how to build a werebear, however, I'm curious.... does anyone know the average lifespan of a Werebear.... or is that up to the DM?
I don't think lycanthropy in D&D changes the lifespan of the creature afflicted with it (at least, I can't remember ever seeing something which says it does).
Of course, since a DM can always deviate from whatever the books might say, it's best to ask your DM (or rule with what you think sounds cool if you are the DM).
Awesome!