One word - autonomy - I do what I want.
When employed I always worked very hard, never off sick. I still work hard I work 10-11 hours days every day but I don't do Fridays.
I think being self-employed is great as long as you treat it like a job/business.
And always, and I mean always put a bit by. The guys I've known who made amazing money but spent all of it and are now scratching around as they are too old or too ill to make that kind of money now.
Being your own boss should be just that, keep on top of yourself don't just float along or you WILL regret it. I'm 46 and in great health but that will not last forever, I've got 15 years maybe working at this rate before I may have to cut back.
The future will come whether you prepare for it or not. Rant over