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Ok my view is slightly different. The pace you are going (4-5mph) is really walking speed or just a little faster. it's a great start. But you don't need fancy trainers for this. Just build up distance,keeping it feeling easy. Speed will come. Bare foot, trainers,heck you could do this in work shoes and it wouldn't matter. Just get out there, walk or run a bit, and at some point you may start to love it. If you get to that point, then worry about trainers, speed, technique etc.