Consistency makes the champion; nothing bedevils the the age group athlete more than consistency killers. Identify and eliminate consistency killers to have your best year of training and racing. 

Gordo Byrn writes about body composition, age and gender, and in his own words: "should be something to offend everyone". Specifically, what is "big" and what is "old"? There are several ways to look at this and each method impacts the risk/return profile of different training approaches.

An in-depth look at the energy systems that pertain to exercise, and especially endurance training. All of these systems must be stressed in ways that are most similar to our chosen goal.

This article by Selene Yaeger talks about how athletes deal with 'imposter syndrome' : the persistent inability to believe that one's success is deserved or has been legitimately achieved as a result of one's own efforts or skills.