My friends and I basically do this. None of us have trust funds.
My friends:
- Park ranger, climbing guide, liftee, etc. Do enjoyable seasonal work, take off seasons you wanna have fun.
- Remote worker. Live in a van, work normal hours, but travel where ever you feel like.
- Rope access technician. Make 6 figures in 6 months, winters off.
- Engineer/Software Dev/Normal Office Worker. Do good work at a no-name mid-sized company for a few years to build up good working relationships and tribal knowledge. Leave on good terms with a handshake agreement that you can return in a few years as long as they still have room for you. Call it a "sabbatical".
- Contractor/Carpenter/Trades. Make 6 figures in 6 months, or just take off whenever you want. Someone always needs a staircase built.
- Accountant. Work 3 months for tax season, then fuck off.
- Travel Nursing. Pick up 3 months stints basically whenever you want.
- Teacher. Summers off.
- Nannying. Build up a string of good references, then take off when you feel like it - you can always find another gig.
- Any job where you can make around 6 figures after a few years in the trenches. Live cheap, save up, invest in passive income streams, retire forever.
Some of them have pets. Some of them have kids. Some of them have partners (who they chose in part for their openness to this lifestyle). Some of my friends were born into stable middle class families. Some were born into poverty with drug addicts. Some were drug addicts who spent years in and out of jail. Literally the only thing they all have in common is that they cared enough about having flexibility in their lives to make it happen.
Edit: for additional context -
Where do they live? They tend to live in their cars or in tents in nature, or else in hostel-like environments when abroad. No rent helps a lot. They will rent out their homes when they are gone if they own. Or sublease their rental if they want it when they come back. Or simply have no home base other than maybe a storage unit. Not owning much, and having little attachment to material possessions helps a lot here, too.
For healthcare - best option is to be from somewhere with a good healthcare system. Lots of my friends are Canadian. I'm from Colorado, and the state subsidizes your health insurance premiums based on your income. You can also use travel insurance, and set your home address to be somewhere where you don't intend to go near, like a parent or friends home. Or you can simply spend all your time in countries where healthcare is cheap or free. Finally, one friend was simply uninsured and said his plan was to throw his wallet out the window on his way to the ER and give them a fake name and address.