I use to run barefooted a short loop near home. From january I've nicely developed some good endurance, as it is reflected on this loop ran at abou MAF speed.
january 7,2km at 6'20"/km (10'11"/mile)
may 7,2km at 5'27"/km (8'46"/mile)
it's just for the record.
MAF pace is a really easy pace you really feel comfortable at.