HSBC just sponsored a big study on changing global attitudes about retirement, with a big chunk on working during retirement in flexible, low-stress rewarding jobs.
http://finance.yahoo.com/columnist/article/retirement/4433?p=1
This is focused on traditional retirees, but it could just as well apply to early retirees.
http://finance.yahoo.com/columnist/article/retirement/4433?p=1
This is focused on traditional retirees, but it could just as well apply to early retirees.