Was this your first attempt at it? Or did you build yourself up to make that mile.
When I first started walking I did it for 10 mins and didn't think about how far I went, then 20,30... I started really walking 2 years ago. Six month ago finally made it 5 miles and and just recently for me to be walking 4 MPH for even 10 minutes stretches on my treadmill. It takes time and effort. Trust me you put in the effort and you will see results. Don't give up the good fight to good health.