How would you fill this gap on my resume?

I don't condone lying, so just... don't? What's done is done: If an employer is stupid enough to hold that 3 year personal wellness gap against you, then move on to the next one. Since you're currently working and almost have 1 year of experience in your current role, I imagine it won't come up too much (and you obviously shouldn't bring it up proactively on your own).

If you really want to cover the gap, you can expand your self-employed startup time to cover this time range.

Here's some other good resources about employment gap:

• "What is the best way to fill my employment gap?"
• "How to properly take career break after layoff?"
• "How to explain career gap due to relocation and burn-out?"

No need to fill the gap, but if you had side projects or courses you took, you can mention those and be vague about the exact timeline.