I have never ran in an organization or on a team before. I've ran the mile once in 5th grade and once in 8th grade. I've been skateboarding 1+ hrs per session, 5+ times per week for the last ten years. Tonight I tried running and ran 5 miles at an easy pace to see how I'd do. It turns out this is also considered an "8k" and I ran it in 42 minutes.
If I were to run an 8k again, tomorrow morning, is it "safe" for me to ramp up my speed so I finish at the 30-minute mark? I don't want to have a heart attack or injure myself.
I'm 17 years old, between 5'8" and 5'11", and weigh just under 120 pounds. I eat a lot of grains and red meat, which I understand do not contribute to a good runner's diet. I'm also male if that affects anything at all.