Death

I ran my first practise 5K , it was about 55degrees. Seemed hot!
I think I died at least twice during the run. I ran from stoplight to stoplight which was 3 miles and then a little more. I checked the mileage in my truck a couple of times...
This was my first "real run." I ran it in 34:15 . Oh my gosh am I slow and fat!! My effort was good and I am bad out of shape! I had to walk twice . First for 30 seconds and the second for 45sec which was coincidentally up hills. I sprinted the last 0.2 miles. It was difficult.
My back began to hurt at about mile 2. I need to get this weight off..
I am down to 275 after 5 months(75 lost).
Am a little discouraged...