tell him to find a product he likes then get a job selling it.

That's how hookers get started. Lol

That's a great industry. Tell me another one where you can sell it and still have it.

Lots of openings for firefighter/paramedics or firefighter/EMTs right now. If he has a clean background and in somewhat decent shape many cities will pay for all the training too. Some starting salaries are in the $75,000-100,000 range and work 48hrs on/96hrs off schedule.

No one wants to do the job these days. Used to have 25-50 applicants minimum per open position and you already had to be certified but those days are going away. Some openings would be over 100 applicants per openings and cities like Fort Worth would have several hundred into a couple thousand show up for open testing. Crazy how times have changed.
A few years on the job and $100,000 plus annually is realistic in some places and that is before OT.

If he's good with people, tell him to find a product he likes then get a job selling it.

Is there an age cutoff for new fire fighters?

It varies by city. Some do, some don't. You can look up some open jobs on Texas Commission on Fire Protection as well as info on what is required to be certified. In Texas to be a paid career firefighter you also have to have EMT-Basic as a minimum certification in addition to your fire certification. Most of the better paying departments will require paramedic certification but might send you to school or give you a certain amount of time to go from EMT to paramedic. It just varies.