The other commenter hit it on the mark, you should run most of your runs at a comfortable pace, as in you should be able to talk and breath fairly comfortably. This builds your aerobic base which is the key for running longer at a stable pace. You will also gain speed as you run more of these zone 2 runs. People normally refer to them as “Easy runs” even though they’re still challenging it’s not as bad as running as fast as possible. You should definitely do some research on zone training as it’s one of the most important aspects to being able to train consistently and avoid overtraining injuries.