When using the Workout app you can only see to statistics at a time. I prefer to see my exercise time and speed; but occasionally would also like to see my heart rate. It's a pain to try and change these stats on the go (tap on the top one, swipe on the larger bottom one); a two handed operation where safety would suggest at least on hand needs to be on the handle bars. Siri to the rescue (if you don't have Hey Siri enabled on your watch, you should). Hold the watch up to your mouth and say "Hey Siri, what's my heart rate". Put your hand back down and wait a 10 to 15 seconds. Look again and there you go, your heart-rate. No need to dismiss it. Leave it alone and 30 or so seconds later you'll be back to the Workout app's display. Yes, it's a bit high considering I'm just sitting here typing. I'm going to pretend it's because I'm so excited to share this tip with you.