Variety is the spice of life. That's why I have so many different hobbies. Whenever I get bored with one, I turn to another, then back again eventually. I knit, spin yarn, sew, and do embroidery. I'm also a musician, but it's my job....not a hobby.
I really haven't gotten tired of knitting though, because I'm always working on about 8 projects at the same time. When I get tired of one project, I drop it and work on another. I keep my projects in separate baskets, so I can pick them up to work on them and set them aside easily.