A work day includes reading and responding to e-mail, calling companies to order parts, taking data from an experiment in the lab. Some days I'm doing only one thing but most of the time I have to juggle several things at once. I never do the same thing day after day. I go work on field trips that can be in interesting places, read papers to learn about new technologies, write papers and reports, and do hands-on work such as electronics, or mechanics. There are a variety of things to do in this kind of research job.
Variety is what makes the job fun.
My hobbies outside of work are bicycling, snowboarding, and a lot of sports. I have two dogs, I guess that I can call them a hobby.