As a former New Ager, I'm certainly freaked out by visualization, yoga, and the like. Perhaps I'm a tad legalistic, but I know how incredibly deceptive practices like that can be, I was blinded from the truth for 29 years as a result of spending 10 years intensely studying eastern religion, visualization, and the like.
Certainly I know that it is possible to use yoga as a form of exercise without getting lost in the new age hoopla, but because of my past experiences, I would simply urge anyone interested in things that are borderline to "the otherside" to be in constant prayer about it, asking the Lord to keep their eyes open.
I've been on that otherside, and frankly I'm so scared to go back, I won't touch yoga or visualization or anything else like them with a ten foot pole. I just don't think it's worth the risk of becoming desensitized, but again, it could be legalism talking.
If you are receiving wonderful health benefits and have found no alternatives, then I wish you happy health, although I would be remiss if I didn't plead with you to be EXTREMELY cautious, and perhaps even consider another form of exercise. Nothing is worth jeopardizing salvation with our precious Lord.
Please, please forgive my strong opinions, but like I said, because of my past experiences, I'm hypersensitive to things radically close to being able to blind people.