Mike... Felt the same way you do! The first week was hard for me too. I hadn't done extensive exercise in 20 years. I'm 43 years old and just decided to begin a lifestyle change. My goal by end of year is to lose 50 pounds and get tone! I have already completed the C25K program and currently I am down 15 pounds. I changed my eating as well... No fried foods, pasta, breads, sweet, sodas, etc.
Definitely don't start until you get proper shoes bc your feet will hurt you so bad and it could set you up for injury. I went to a store called Fleet Feet and they helped me get the proper shoe. I use the Nike app and rockmyrun app. Both are great!
You Can Do It!! Best of Luck!