Subtract your age from 180. Run at that heart rate. Another formula 0.7*(HR max — HR at rest) + HR at rest If you don't believe in formulas, run at a pace in

Subtract your age from 180. Run at that heart rate. Another formula 0.7*(HR max — HR at rest) + HR at rest If you don't believe in formulas, run at a pace in which you can hold a conversation or speak a few sentences without losing your breath.