female, 26,130lbs, no health problems & average body. First day of me doing c25k. The 2 other times I've tried the program I only made it a few Weeks in because of killer pain in my ankles/achlles that left me unable to heal for awhile. note those two times were on the treadmill and will be again this time. Advice starting off and not injuring myself again?
I suggest changing your foot strike and stride. Shorten your stride so that your foot falls (when your feet hit the ground) are directly under or just in front of you. Try to maintain a rhythm of 180 foot falls per minute. Seems fast but it is very efficient. Shorten your stride and try to land mid to fore foot. You will find that you are pushing to the rear with your ground foot propelling you forward rather than kicking your foot/leg out in front of you to achive a long stride.
I can attest to what many pros have written, this works! Take your time and practice perfecting your form. Once you get the rhythm, you will know you have arrived. You will spend less time bouncing up and down and more time efficiently moving forward smoothly.
I hope this works for you, and if you want to read more, try reading "Born to Run" and "Eat and Run".