hey there, if you weren't aware there is a whole yoga/meditation forum out there. they might be better at explaining it to you. i don't go by all of the hype and mumbo jumbo that a lot of people today do. i just do it in the mornings because it feels so good to stretch yourself out and it helps me to wake up. in a way it has a spiritual depth to me, but i think for everyone it is something different and can't exactly be contained in a neat little box. that is just my opinion though, so form your own. good luck with your search.
My favorite yoga is Ashtanga (Power Yoga) and I can tell you that it, and other forms of yoga, are great for stretching, breathing, strength building (more so in the case of Ashtanga), flexibility as well as relaxation. Any person who works out needs to work on these things, and yoga is a great way to combine them. I've known many people who were doing professional sports for many years and are in great shape who started doing yoga just for the stretching but stayed for a lot more! I have a friend who races on sea Kayaks and he says that he now uses yoga breathing techniques all the time. Old people can regain the flexibility of their youth, and young people can face aging in the best shape possible so it doesn't hit them as hard. It also gives you grace of movement, a better posture and peace of mind if you practice it correctly. Just do it and see for yourself!
i love yoga because it helps to clear my mind and it just plain feels good! nothing better for starting your day than 10 sun salutations!