First off, I love being a paramedic, am not burned out, and love my job and where I work. I am 10 years in and realize I may be the minority with my outlook so do not take this as a rant from a burned out EMS provider who is stuck in a dead end job.
That being said, if you want to have a career in EMS, you should consider.....
The emotional toll:
Be forewarned: you need to realize EMS oftentimes takes more than it gives. You will realize that dealing with people's lives and seeing human suffering and tragedy will change who you are as a person. If you see the world through rose colored glasses, those will come off very quickly. No exceptions! There is no person alive who can not be affected by the types of things we see and the frequency with which we see them. Granted it is not an everyday thing, but you will see dead kids, child abuse, horrific injuries, senseless acts of violence etc. You will arrive on scene with the best of intentions and be kicked, punched, spit at and called every name in the book. We go into disgusting homes crawling with insects and packrat conditions on an almost daily basis. We deal with people who if you were off duty, you would probably cross the street to avoid. That is the nature of the beast. You will not save that many lives. You will see a lot of messed up things. That which the general population fears is our reality and you confront that reality every day. You will see the dark side of human nature, one that most people do not want to admit exists. It will change you as a person. Your personality will change. Your friends will change. Your paradigm on life will change. I am a completely different person than who I was before EMS. Whether that change is good or bad is a matter of debate.
Where you work affects you a lot:
Go work an agency that you get to be actual EMS at. Consider call volume, scope of practice, variety of calls, pay and benefits and opportunity for advancement. Sometimes, it may involve moving to a different city or state. Go out of your comfort zone. If you want EMS to be a career and are in it for the long run, that sacrifice and relocation is oftentimes necessary. It is necessary for many careers, and EMS is no exception.
Especially if you live in SoCal, but this applies everywhere: Do NOT work for a shady transfer only company because it is convenient/close by/easy to get hired/etc. You will burn out quickly. You will lose your skills. You will not be actually doing EMS if all you do is discharges and dialysis all day.
Avoid the pitfalls
Finally don't become complacent. Complacency kills everything in life, whether it is relationships, your happiness, or your career. In EMS the stakes are higher and can kill your patient, your partner, or yourself. If you are an EMT, look to become a medic. If you are a medic, NEVER stop learning. Th day you stop learning and trying to better yourself and become complacent, is the day you should leave EMS.
Also do not become complacent with scene safety, that can have disastrous consequences.
Anyway, sorry if this post came off as a rant, but that is my advice for people considering EMS.