and although sian pierre says he didn't really appreciate that as a kid, he clearly does now.s fired at 75, sian pierre started showing his gratitude in the sweetest possible way ♪ ♪ he took her bucket list and together they started ticking off items one by one-- milk a cow in vermont, done. take a hip-hop lesson from a "hamilton" dancer. check. learn to use instagram. getting there. >> here we go! >> reporter: he even flew his mom back to her native england to throw a penny off a london bridge and visit her sister's grave for the very first time. a lot of the list is things she could never do juggling work and kids. most recently, they walked the entire length of the boston marathon thon because after years of cleaning rooms for all those runners, she just wanted to see t i never felt more loved. and, actually, i'm excited about going and seeing the next-- the next chapter. >> reporter: and that's how sian pierre thanked his mother for putting up with his thanklessness. but he says he received an even bigger gift-- a lesson on love. >> you can't feel it when you're just runni