[yoseph]

> Startup is just your job.

I disagree with calling it a "job". It makes it sound like something you don't want to have to do.

IMHO, I think you should be passionate about your startup. It shouldn't feel like a job but something that's enjoyable to work on.

But, back to the main question.. if playing the piano keeps you sane, do it. Stress relief is way more important and will pay dividends long term to both you and your startup.