I was a 14:50 5k runner at age 19 with low mileage 40-50s. A string of injuries caused me to hang up the spikes for a few years and focus on strengthening the rest of my body. At 24 years year old now what should i aim for if i try to make a cumback? How much time could i drop from just being older / being able to train at more than 50 miles a week without getting injured?