Retired at 50, hated it (probably not mature enough) and started my own business six months later.

Re-retired at 64 and love it. I have no trouble in finding things to do, including the very important (to me, at least) privilege of giving that very valuable (again, to me) commodity, my time, as a volunteer.

It's all about choosing the right time for you (and making sure the the finances are sound, of course), but the problem is you'll never really know until you try it.