I've had a lot of jobs in the past. First was as a golf caddy when I was about 12.
Have worked in a scrapyard searching (through mountains of metal) for non-ferrous scrap, briefly as a commercial fisherman, numerous gas-station/convenience store jobs, telemarketing (sucks and I'm terrible at it), inbound telemarketing filling out credit card applications, delivery driving, dish washing, yard work, general labour, probably others.
I've never managed to hold a job for six months. Usually quit or fired within three months. Sometimes only days.
Never managed to make enough to do more than just survive, really. Or managed to figure out how to do anything more than just barely survive. Not sure if I've ever had anything that would qualify as "gainful employment".
Currently on SSI.
Honestly I'm pretty scared of getting a job, even if someone was hiring for something I'm capable of and was willing to hire me. I feel like I'd probably get the job, lose my SSI because of it, and then lose my job and my place in a fairly short amount of time and end up spending a few more years on the streets before finding my way out of that mess again.
I really don't like being on SSI, but it is far better than some of the alternatives, and until or unless I can figure out something better I'm really thankful to have it.