David, Thank you for the response. Wow! 50 miles a week, that great. I am walking about 150 minutes per week and still not feeling great. I decided at the time to forgo the Cardiac Rehab due to my fear of Covid. I called the cardiac rehab and the gentlemen that answered the phone said just change your diet and walk 150 minutes per week. I think I need to go to rehab now. My chest hurts when I walk and I have to stop and take a breather, then continue. Well, thank you again. I appreciate it.

Most Important - talk with your Doctor and Cardiologist to plan what you need to do next. In 2010 I was having Chest pains while walking to work in Gatineau QC from Ottawa. Even though I was careful with my diet and exercised regularly.
My doctor immediately sent me to a local hospital but they couldnt do the necessary nuclear scan so I was sent to the heart institute in Ottawa where I was discovered to have a failing Atrial Valve and two block arteries (100%). I was scheduled for heart surgery within a month and had a success Atrial Valve replacement and two arterial bypasses.

After this I was put on the Cardiac Rehab exercise program and was directed to walk 4 miles per day.

I am healthy today except for my Type II Diabetes which is in the pre-diabetic stage because I walk 50 miles per week and follow a strict diet.

You need to see your Cardiologist. They have medication and they may need to do something else. You shouldn't be in pain.

Go see your cardiologist. Why put it off. Your chest hurting when you walk is not normal