No, I’m not being sarcastic. I mean it.
Artists and craftspeople are a strange bunch. We tend to work long hours, are very wrapped up in our work and quite often we came to the business of craft or art through a pastime that grew. When your hobby becomes your job or profession, it ceases to fill the function of “hobby”. Ergo, you need a new one (even if you don’t think you do).
Side interests or extracurricular activities are an important part of a person’s life. At some point as you grow up, you realise that your university degree alone is not what will get you a job or make you good at it. What actually counts is the personal experience that you bring to the degree and the way in which you use your cumulative education to perform your chosen life’s work.
Artists and craftspeople (artisans, if you will) are no different. A mastery of skills and an ability to transform concept into tangible object needs to be supplemented by a vision or ideas that require transformation. An artist without side interests and curiousity creates their own artistic void, the kind of void that gives rise to the, “I need to create something, but I have no idea what to do,” conundrum.
Quite apart from sources of inspiration, side interests (I actually rather dislike the term “hobby” as it sounds superficial) can allow you to fulfill other aspects of your persona. Being isolated in a studio for long hours is a personality trait that many artists share, but most of us still reach the point periodically of needing to talk to real, live people. Don’t underestimate the virtue of simply getting out of the house!
Finally, and this is the real point, they get you doing something other than work. This is why your hobby or pastime needs to be different from how you spend your working hours. Many people have overlaps between them (a landscape artist whose hobby is photography and hiking, for instance), but they should be different enough that you switch gears and forget about work for a while.
To improve your work in the studio, try getting out of the studio for a bit consistently. The results may surprise you.