I learned to crochet when I was around 7 (I crocheted several ripple afghans during my childhood, and a few other afghans and lots of baby blankets in adulthood); soon thereafter my mom taught me how to knit, but I hated the boring gray acrylic yarn so much, I dropped knitting and never picked it back up...until last year.
My hand was starting to cramp while crocheting with small gauge crochet hooks, so I re-learned how to knit. For me, continental knitting style meshes well with my crocheting habits. I checked out a library book for kids, knit a swatch, then made a couple scarves and hats (while consulting on-line video tutorials), then stopped b/c knitting for me was so slow it was discouraging (I did love the straight and circular bamboo needles I was using, though).
At the end of summer this year I decided to get a head start on crocheting a bunch (dozens) of hats and scarves for charity. As long as I stuck to larger crochet hooks, my hand was fine; however, I totally burnt myself out on crochet, so now I'm back to knitting.
I knit my first pair of socks on a set of metal dpns and noticed my speed had increased, but I didn't like "wasting" all that time switching stitches to different needles. I was glad I knit the socks, but was definitely not going to bother knitting another pair. I wanted to try something different, so I knit my son a raglan sweater (he's too young to care about the mistakes I made). Then I knit myself the Scotty hat; after that a plain scarf; now I'm challenging myself by trying a new-to-me stitch pattern, different yarn, and metal needles. Then I found a link to the Yarn Harlot and spent an intensive couple of weeks reading all her archives (they go back to 2004), gaining a new perspective on knitting and wool.
I've only just gained the confidence with knitting to try doing it while watching TV (well, a DVD I've seen before so I'm not constantly staring at the screen). I still need to recount my stitches rather frequently--lots of interruptions by DS mean I'm losing my place quite a bit--but that doesn't take too long with a scarf. I doubt I could ever bring myself to knit an afghan or baby blanket--those will always be crocheted items for the speed. It still bugs me that knitting is so much slower than crocheting, but at least now I've realized that a purled row takes me less yarn than a knit row, so I can steer clear of patterns requiring lots of purling if I'm in the mood for speed.
I enjoy working with yarn to produce something useful, but mostly I crochet and knit to relax (I've noticed I get grumpier when I don't get enough yarn time during the colder months). It's rewarding for me to learn new skills/stitches, or attempt a new article of clothing (I'm still in the planning stages for my future shawl collar cardigan). I like having tangible proof that my brain hasn't turned to mush, and knitting and crocheting feel more productive than reading (which is my all time favorite activity). However, it'll probably be a few years before I can safely attempt something really complicated like color work or extensive charting; I don't believe in setting out to fail, and until DS is older, that kind of work would be doomed on my needles.