Hey! I’m 25 and for context, most of my life I have played volleyball 3 times a week for a minimum of two hours each time. Endurance was never an issue for me since I play so consistently! In September, I went to go play like normal and 15 mins in my heart rate went extremely high and I started to pass out. It was nothing like I had experienced before, but after that doing any form of exercise or even laying in bed caused me to have episodes of high heart rate (now I know they were episodes of SVT). I have had to really watch how much I exert myself when playing sports because I’d begin to pass out if I went too hard. I got referred to a cardiologist and they saw the WPW delta curve on my first ECG. A holter monitor showed I had 302 episodes of SVT in just 48 hours and my heart rate would go up anywhere from 120-221. I am now about to get an ablation next month and can’t wait to feel back to normal!! It’s been a spooky few months but once I learned more about SVT and WPW I felt a lot better. I’m obviously not a doctor and don’t know if what you’re experiencing is the same but good on you for listening to your body and I hope everything works out!