Keeping in the Aerobic Heart Rate Zone?

Sarahs2576

When monitoring your heart rate during a workout, how often should you check your pulse to keep yourself in a specific heart rate zone? I'm trying to keep myself in the Aerobic Zone which for me personally is 128-147 bpm. I don't want to stop every 2 minutes to check my pulse or have a death grip on the sensors of the treadmill during the whole workout and was wondering if anyone had a suggestion for me on how often I should be checking? Thanks!