Why is Yoga so painful?

I was with my aunt yesterday and she recommends that I do yoga to relax and meditate. So it’s the evening and we start with the Downward Facing Dog and then the Triangle Pose. The seated forward pose and the Upward Facing Dog and even the Dolphin pose were painful.

Yet my aunt can do the poses incredibly easily and considers them relaxing. She’s been doing yoga for over 20 years and is 60. I felt terrible as I’m 5’4 with a slender and athletic build. I’m only 95 lbs. She on the other hand is 6 feet with longer limbs and felt that should practice yoga so that it isn’t painful

So the question is should I continue with yoga or will I continue to hurt my back and spine. My 1st time trying yoga I didn’t see it as meditation but rather a painful workout.

Btw she’s not my biological aunt but my dads brothers wife. Though she has the same build as me only 8 inches taller.