How does Athena act as a personal trainer towards Telemachus in book 1-3 of the odyssey?
Athena, disguised as Mentes, claims that Odysseus is still alive. She then tells Telemachus to go off in search of his father. She tells him not to cling to his childhood anymore, that he is now a man, and that he must stand up to the suitors. Her talk with Telemachus "left his spirit filled with nerve and courage, charged with his father’s memory more than ever now." In Book II, Athena (disguised as Mentor) becomes like a mentor. She inspires Telemachus again and gives him hope regarding his upcoming voyage. She even acquires the ship and resources he will need.
In Book III, when Telemachus is feeling despondent and skeptical at the prospects of finding his father alive, Athena reveals that she fully supports Telemachus in his quest. When she does this, Nestor also shows his support:
“Dear boy—never fear you’ll be a coward or defenseless, not if at your young age the gods will guard you so."
A good bit of this "training" is giving Telemachus support and a sense of hope.