Howling:The Doctor starts running: Sound of Drums vs. Name of the Doctor

In The Sound of Drums/Last of the Time Lords The Doctor says that his journey started when he was a child, however in The Name of the Doctor we see The Doctor as an old man with Susan stealing the TARDIS for the first time. Is this really a continuity error? My theories:
 * 1. He was young by Time Lord standards, taking into consideration that Time Lords live way longer than humans.
 * 2. He was referring to the fact he was in his fist incarnation.
 * 3. "Rule Number 1: The Doctor Lies"-River Song