Yes, a heart check sounds like a good idea.

Also, one thing I forgot to mention is that a lot of people find that, initially, they can only achieve the protocol's specification for a few minutes. After that, either their cadence drops or their heart rate gets too high. Some people in this situation have found that if they build up slowly over a period of weeks, they can eventually achieve the full specification.

Different people use different methods to help the time pass quickly (music, video etc.). These days I listen to the morning news/current-affairs programs on the radio.