Hi! I just did the NYC Marathon for charity. I've been running for decades but never competitively, except for the run portion of triathlons. Now I'm hooked on the marathon and I really want to qualify for Boston; a few of my friends and coworkers will be running it in 2020 and I'm making it my goal for next year. I ran NYC in 3:57, but I made some rookie mistakes, particularly with nutrition. My longest training run was 21 miles at 8:28/mile and 1,500 ft of elevation, and I was maintaining around 8:33/mile for the first 15 or so miles of the marathon and feeling great. I took in more gels and hydration than I normally do and my stomach was in agony from mile 17 to the finish. I should have known better; I never eat after mile 40 on the bike during a 70.3 triathlon because my stomach doesn't tolerate much while running. But I had never run more than 21 miles and was really worried about bonking. Aside from long runs (16+ miles) I never eat or drink anything during weekday training runs, usually anywhere from 5-10 miles first thing in the morning.
Anyway, I learned my lesson and will play with nutrition/hydration during long runs in the future. Now I need to learn how to train. I have seen a ton of training plans online and have no idea how to choose one. Where should I start? My 10K PR was 45:50 at the end of an Olympic distance tri. I was training roughly 40 mpw recently, but not following a specific plan the way I normally would for triathlons because I was just doing this for fun and to raise money, not with any real time goal in mind. BQ for me is apparently now 3:35, which I think should be attainable if I bump up my mileage and follow a plan?
I would appreciate any insight and advice about where to begin! I was thinking I would plan to run one marathon this spring and one in early September. I also plan to sign up for a triathlon or two because I actually think I am a better runner when I am cross-training. Any thoughts? Thanks in advance!