This is such a good article about early retirement it's worth revisiting every now and again to get a reminder of the need to keep busy and mentally/socially/physically engaged once you leave the work force.
While everyone is different, for many (including me), planning a degree of structure into my days is a must. Goals matter in part because I didn't retire from my job - I retired to a different lifestyle and to priorities that were different from earning money. I didn't retirees I could sit on my butt watching TV and eating junk food all day.
Philip Greenspun Early Retirement