Part 5/10:
This straightforward method provides a rough estimation of your maximum heart rate. Subtract your age from 220, and from there, multiply by 60% and 70% to find the bounds of your Zone 2 range.
For example, a 30-year-old would subtract 30 from 220, giving a maximum heart rate of 190. Multiplying 190 by 60% gives a lower Zone 2 boundary of 114, and 70% gives an upper boundary of 133.