Yoga is an ancient practice that involves physical poses, concentration, and deep breathing. It can be traced back to northern India over 5,000 years ago. The word yoga is derived from the Sanskrit root yuj, meaning “to yoke,” or “to unite”. The practice aims to create union between body, mind and spirit, as well as between the individual self and universal consciousness.

As Muslims, our goal is never "union" but rather the worship of Allaah.  And, Allaah has directed us to acts of worship that He loves and is pleased with.  We have an act of worship that involves physical poses, khushoo, and remembrance of Allaah.  Which is better - salaah or yoga?

For additional reading:

What Is the Ruling on Yoga? - Islam Question & Answer (islamqa.info)