Do what you love to do and give it your very best. Whether it's business or baseball, or the theater, or any field. If you don't love what you're doing and you can't give it your best, get out of it. Life is too short. You'll be an old man before you know it.
Managing can be more discouraging than playing, especially when you're losing because when you're a player, there are at least individual goals you can shoot for. When you're a manager all the worries of the team become your worries.
The manager is by himself. He can't mingle with his players. I enjoyed my players, but I could not socialize with them so I spent a lot of time alone in my hotel room. Those four walls kind of close in on you.