What do I need to know about obtaining a work visa in Thailand as a personal trainer and yoga teacher?

Very simple. Get a job first (find an employer who will employ you). Then they'll do the paperwork for you. But unless you have a profession that a Thai person cant replace you, you will have close to zero chance unfortunately

@Tom ******

you already have an employer then they will do the paperwork

currently many bar managers in Soi 6 are wanted, you can drink all day and play best friend for tourists and expats who visit the bar

Nice dream Mister Cohen

You need to find a job/employer in Thailand who will send you paperwork so you can apply for a work visa. They will also apply for a work permit for you to work for them.

That's how you work in Thailand. You need a work visa and a work permit that's linked to a specific employer, both of which can only be obtained AFTER you already have a job.

Freelance/work for private clients isn't a thing for foreigners. Even if you started your own company, you cannot get a work permit for yourself until you have 4 Thai employees.