Day 2 from couch to 5K

Yesterday I tried to do from couch to 5K. it is a half an hour work out and I could barely do 15 minutes. My legs were burning, feet aching, and back screaming at me. How the workout goes is a 5 minute warm up, then 20 minutes of alternating jogging for 60 seconds and walking for 90 seconds. I could barely get through 15 minutes including the warm up. Today I did all 30 minutes including the 5 minute cool down. It hurt and still hurts though I have been done for an hour. But I am glad I did it. Even though I didn't really jog as much as I was supposed too. But what do you expect from a 344lb woman. Lord I pray I can keep this up. Help me God.