Before you begin
How to Fit Training Into Your Busy Life
HOW HARD SHOULD YOU GO?
PERCEIVED EXERTION (PE): 1 2 3 4 5 6 7 8 9 10
1: not remotely challenging;
5: breathing deepens and conversation is tough;
10: as hard as you can
And when you rest? Recovery between intervals (RBI) doesn't mean stop; it means go super easy and catch your breath. Aim for a PE of 1–2.