Being able to make choices, determine the best path of action, and (if you work hard enough) make something great.

Right now the best things I make are balloons (but I do have some fun side-projects).

Sounds to me like you're in a good opportunity to start your own start up. I might be being a bit presumptuous here but it seems like you have undemanding job but one that pays the bills none the less, this is a perfect time to begin working on your own business as long as there aren't any contractual difficulties.

I have to say it does sound very Zen, balloon making. In life, I have found that the trick is not about how to keep the mind busy, but about how, how often, and when to get it at ease.

It's Zen until someone walks in asking for a 40 balloon set, while there are 4 people in line for the register still.

The part where investors fall over themselves to throw vast amounts of money at you?

Of course, being a dream, this doesn't happen to the vast majority of startups...

Not the OP, but the ability to control your own destiny? :)

Investors, stakeholders and clients control that destiny.

everyone's got a boss, in some measure, but not every "startup" has investors. and, if/when you're the owner, you have more choice in which clients to serve, vs the OP working retail.

Customers... and employees everything else takes care of itself, IMO. Not being able to make a small significant change demotivates you significantly.