OK I have some first hand experience here, I quit my job 2 months ago and am now unemployed.
I have enough money to live on for a while and I dont have any pressures to get back to work. Summer time is here.
So am I sitting in the garden doing nothing getting a sun tan, yes. But Im also working on all kinds of other things like learning computer programming, building raspberry pi prototypes for a crypto project, presenting my work at conferences and conference calls.
Im donating blood more regularly, sorting out stuff on my house, getting fit at the gym and seeing more of my family, am a much happier and more motivated person.

I think the modes of office work we have now will be looked upon by future generations as very unhealthy; like we look back on factory work of the 19th century; dirty and dangerous.

There will always be two outcomes of UBI; the lazy, entitled and degenerate will waste their UBI on cigarettes and alcohol while their kids go hungry, but they are a minority. Most people will do things they feel are valuable for their family and community. People dont like being idle.