No patient, no call, no job(employment type, not run type) will ever be worth your personal health and safety. If your employer doesn't understand that, find a new employer. I blew my back out 12 years ago humping dialysis patients to and fro for a crappy private that didn't care one bit about me.
The "ems diet" is fun to joke about when your 19 or 20 and your metabolism is firing along at full speed. It's not funny when your weight and cholesterol are in a neck and neck race for 300 before you're 35. Learn how to eat properly and find a better way to deal with stress than junk food and cigarettes.
Never get comfortable. Always be looking at the next step. Whether its the next job, the next cert, perhaps even the next career choice. Always be moving towards a goal. When you stop trying to get somewhere, you stay where you are. That may be fine if you're the chief of the trauma surgery department at Hopkins, but its a terrible plan when your a basic emt barely making the rent.
Know when to turn it off and go just be a regular person. You dont have to be the hero 24/7. You're allowed leisure time and that leisure should be outside of fire/ems.
Understand that, bls or als, you will very very rarely actually pull someone out of the grave and have them saunter off into the sunset. Hero moments are almost non existent. This job is a daily grind of small accomplishments. If you cant hold an old ladies hand on the way to the hospital and find value in it, go do something else.