I was pretty mediocre and never was close to be nominated for anything like that. Goofed around through middle school (barely passing in 8th grade, GPA was probably 2.2 or 2.3) and then high school was catching up. Probably never ran faster than a 7 minute mile, but did run 6.5 for the 50 yd dash, 1:50s for 600 yard run (somewhere in the 80-85% range for President's Fitness test).
High School: Graduated with about a 3.35 GPA (but 3.6 for junior and senior year), working just hard enough to get decent grades. Our class (public HS) had 7 National Merit Scholars out of a class of 250. Only ran a 5:30 mile.
College: Somehow got into a higher rated school (top 20)--with a lot of very smart people--and wallowed in more mediocrity, but passed all my classes and graduated in four years. Undergrad GPA 3.0. Ran a 4:32 mile.
Grad school: Got a funded program into one of top schools in my field of interest and did decent academically. 3.6 GPA, with a couple Bs in upper level undergrad classes, which were harder than the grad classes. Ran a 4:24 mile.