How do I begin to let myself “untense” or live freely? I people please to the point of exhaustion…

Thank you for asking your question and articulately stating how you feel! 

My first thought is that you need to listen to your instincts and let your intuition guide you.  First and foremost.  If someone asks something of you, for example, 99% of the time, you can mentally talk yourself into or out of anything.  If you are so focused on what others think and how they perceive you, you are leading with your mind and not your heart or your instincts.  Rather, lead with your feelings.... not your thoughts.  If you are searching for answers, let your feelings guide you.  What does your gut say? The more you do this, the more it will become a habit.  I would start there. 

I would shift the focus in your life back to yourself; your needs, nourishing your body and mind.  Do yoga.  Get into nature.  Read a book.  Take a bath.  Talk to people and do things that spark joy for you.  Take a break from those that stir up negative feelings/anxiety.  I've been a life long people pleaser and it is a habit you can absolutely break-  Your unique beauty, energy and vibration will not mesh with everyone's vibration.... and that's ok.  That's what makes up a beautiful and complex world.  If someone isn't on your wave length, send them love, but stay in your peace-  You will not be everyone's cup of tea...  that's not possible.  But you will matter so much to certain people... and that is what matters most.  Continue to try and live an authentic life as much as possible.  You will let some people down.  You will annoy others.  You are not responsible for how other's perceive you.  That is their dream... not yours.  Practice authenticity and vulnerability whenever possible. 

Also, try and do something that gets you out of your comfort zone.  Something just for you...  We only truly grow when we are uncomfortable.  This requires bravery and.... well, feeling uncomfortable.  But, like listening to your intuition, in time it will get easier and you will see so much growth.

I hope this helps and wishing you so much luck and love on your journey.