I am 24 have been working muliple jobs for almost 10 years! It has both ups and downs. 1. your always busy and have something to do... but you dont have time for your self to just relax.  2. The cash is always coming in... but you spend it just the same with transportation, food, coffee, and anything else that you need when the stress builds.  3. You meet and interact with new and exciting people... but then you come accoross the mean spirited, down trodden side of society, you will encounter all the crazies that range the whole specturm. Also- you get tired to seeing people - sometimes you dont want to put on a smile for that lady complaining about whatever she feels is a conspiracy against her.  Then you start to miss your friends... its a sad cycle of life.

In my opinion - it doesnt hurt to work more than one job - if you can handle it. But you have to negotiate a work life balance with your employeers and family.  If you happen to be lucky doing at least one thing you like  you have to take as much joy out of it as possible.  You have to make the most of it. Then you have to decide when one of those jobs is going to be you working for yourself.