It is when you level up! Lol yoga is the more physically conditioning aspect of spiritual training with it comes more learning and experiences, yoga is not to be taken lightly it is just a part of a while, if you want relaxation look up gurus and spiritual leaders actually Jim carry just experienced enlightenment in the past couple years look him up on YouTube
Look on YouTube. There are some yoga videos that focus more on relaxation.
You're probably not performing the poses properly....try "Daily Yoga" it's free & show you how to perform each pose w/audio & visual to coach/guild you thru each sequence....
Have someone check your posture. You might be doing something wrong.
There are many dangers associated with yoga. I would do my research before going any further.