Many of the baby boomer generation are doing just that! As you get older life experiences change your way of thinking. In other words, the career that you loved in your 20's is no longer fulfilling for you at 55. Why not change? Go to adult education classes, volunteer for something that you are passionate about, let your imagination run wild .... if you don't do it now, then when?
Your children are grown and out of the nest (unless you have a boomerang on your hands!) and hopefully you are financially secure enough to go out on that limb. Some people may try to convince you that you are crazy, do not listen to them!
Don't let life pass you by until you aren't able to go grab that brass ring.
A friend once sent me this advice:
intention of arriving safely in an attractive and well
preserved body, but rather to skid in sideways,
chocolate in one hand, champagne in the other, body
thoroughly used up, totally worn out and screaming
“WOO HOO what a ride!”