I practice yoga with the Iyengar school. The practice certainly has hindu origins, but I think very few of the hundreds of students who practice where I do would consider themselves hindu.
Doing the postures (asanas) naturally teaches you about your inner responses, and leads towards a patient mindfulness. Much of the benefit comes from dealing with the induced stress of mastering the postures, paradoxically. When you challenge your physical habits, and the current flexibility and strength of your joints and muscles, the practice becomes a very personal encounter with your physical, emotional and psychological habits.
This encounter with yourself happens within the framework of disciplined physical activity. The frame of reference is your body and mind in the here and now. So it is not inherently related to any particular religion or philosophy, except by history.
Simply put, the activity itself produces not only improved health, strength and flexibility but also a calmer detached overview of your reactions and responses to stress. The practice also includes some instruction in meditation, usually in the period of complete rest at the end of a class. The meditation instructions do not include any religious philosophy or language, the aim is deep relaxation and remaining mindful. I cannot see that being in any way incompatible with being a christian.