The first step in any conditioning programme is to build an aerobic base.
This requires two to four sessions per week of continuous aerobic activity (e.g. jogging or brisk walking) for 15 to 30 minutes at a moderate intensity.
The target heart rate for many people during this form of exercise is approximately 130 to 150 beats per minute or a perceived exertion of “moderately hard.”
Faster is not better.
As long as you get your heart rate into the target range, running a 12-minute mile or a 6-minute mile produces approximately the same aerobic and caloric effect.
A minimum of four to six weeks is generally recommended for a healthy young adult to build an aerobic base.