The key to a happy retirement may be . . . not retiring. Work because you want to, not because you have to, to achieve balance, health, and purpose in your life after full-time employment.The rules of retirement have changed and there’s more at risk than ever. People are living longer and have to finance as many years in retirement as they had in their entire working career. So what will thirty or forty years, or more, in retirement look like for you?The ol...