Using Whoop here, but it's quite expensive and it needs quite a lot of trust of me for having my health data. But ok...it helps me to stay focused with metrics on my overall well-being and for 90% it is accurate how I feel. Listening to your own body is always the most important, but using these metrics helps me to improve my fitness levels towards achieving competive (cycling) goals.. I can see how my fitness improves / declines over a longer period of time.