Keep in mind, there are multiple kinds of Yoga. There's Hot yoga (practiced in a hot room), Bikram Yoga, and the gentler/more relaxed Chinese form of Yoga. Yoga is definitely good for static (long term position holding) strength, a kind very useful for every-day posture and health, as well as holding your position while skiing or rock-climbing.
You might consider Tai Chi from a healing-focused instructor. The movements are designed to be very gentle and restorative, but over time the movements do build muscle in a gentle way. The deep understanding of the movements can also be used for self defense if you train with an instructor who has focus on that, or you eventually train in other martial arts as well.
There is also a focus on static strength in most of the widely-practiced forms of Tai chi, vs the Dynamic Strength used for jumping, or quickly punching or kicking.
I'd stay away from anyone who starts talking about dolphins, or who's introduction to the art involves talking about "cosmic energy" instead of focusing on the movements though.