Running is not training. Running is a stimulus; training is the response of the body to the stimulus. You want to come up with an ideal set of stimuli to create an efficient training response.

Outside of a goal race, you shouldn't suffer when you run, especially 'a lot'. You are tearing down muscles and training energy systems that are inefficient.

Slow down. Walk. Fragment runs into multiple runs. Run doubles. You'll get faster, faster. Add volume at your new, sane pace and new, sane volume up to 40-60 miles/week.

Once you've achieved the slow end of 'adult fast', say sub-20m/40m/90m for 5k/10k/half, you can revisit suffering during training. You still probably shouldn't.

Of course if you want/like to suffer or can only run 4 times a week at peak heat during a Georgia summer then all of this is out the window.