Why do both? 

Combining yoga with weight training and other types of fitness classes is not only a great way to help you prevent injuries but it also helps you tap into equal amounts of flexibility and strength in your yoga poses. In other words, it allows for greater muscle awareness and a more balanced approach to your yoga practice.

Weight training combined with yoga practice can also be a great way to maintain strength as you age. Countless studies show that a lack of exercise can lead to muscle mass decline beginning at age 40. Lifting weights two to three times per week builds muscle and bone density and helps with balance - which in turn will benefit your yoga practice! 

Lastly, it's important to introduce your body to new challenges from time to time to avoid hitting a plateau. Adding just a little bit of weight training, pilates, or other types of fitness classes, to your routine will give you extra oomph in your poses, give it a try!