It’s not all that surprising that playing Rick goes down as the most exciting and challenging role of his career.
Prior to landing The Walking Dead, he’d mostly worked on British projects that didn’t run for all that long and lacked zombies.
Based on the contents of his letter, Andrew Lincoln doesn’t regret sticking around longer than his original intention, and he certainly doesn’t seem bitter that Norman Reedus didn’t stick with their earlier pact that they would leave the show together someday.