Feeling fatigued after YTT200

Hi folks. I got my YTT 200 last year because I wanted to have it in my arsenal of tools. However I didn’t love or enjoy it. I know yoga is incredibly amazing and am struggling with where to go from here. Something happened in my body after turning 35/37 where my muscles ache so much I end up giving up on the class or poses. Yoga used to be so easy for me up to my early 30’s and now feels heavy. The girls in my class didn’t understand the tension in my muscles and the exhaustion I felt after every class. So having said all that, I have been doing Charlie Follows at home and love her videos on YT, but want something more challenging so I can build strength and stamina and to refresh my YTT. CF’s videos are so soothing they put me to sleep 😆 and I find them a bit repetitive. Has anyone faced similar challenges? How do I continue practicing to get better? I forgot what I studied (I still have my book tho). I’d like to get back to feeling strong and capable and don’t want to feel like I wasted thousands of dollars. I would also like to teach at some point but having a hard time with confidence atm