. >> story of noah and lucas aldridge.off on twitter and youtube. >> absolutely. more than 72,000 views of this inspiring example of brotherly love. >> we're a very active family and love to run and bike and stuff and we want him to be a part of that. >> reporter: the aldridge family heard about the ymca kids club program and a kids triathlon and that's when noah had an idea. designee said mom i want to do this with my brother. that's where the idea was born. the next day we started training. >> reporter: running, biking and swimming together to get ready. 8-year-old noah pushing and pulling his brother right along with him. >> he's just going to be happy that he did it. >> reporter: when the big day came, the house was ready to roll. noah was nervous. >> i'm scared because i haven't done it with lucas before. >> they will start with a 200 meter swim. >> we have this cord thing that goes around me and it snaps to a raft that lucas is in and i just swim. >> reporter: and swim he did. as hard as he could with his brother in

. >> reporter: inside their idaho play room, lucas aldridge and his big brother, noah, share a love for "star wars" -- >> where's my light saber? >> reporter: -- and each other. >> well, just makes me happy. >> reporter: their special bond can be seen in baby photos back when lucas was diagnosed with a rare disorder that affects brain development. now 6 years old, lucas can't walk or talk or feed himself, but he sure can smile. his biggest grins reserved for noah. >> i love him. he's perfect. >> i start to well up, almost cry every time i hear him and his passion for his brother. >> reporter: so as noah trains for a kids' triathlon, he knows lucas won't settle for the sidelines. when the big race day arrives, these brothers tackle the triathlon in tandem. never mind that a few months ago noah couldn't swim at all. today, this inspired 8-year-old is paddling for two. after four back-breaking laps in the pool, they hit the road for one and a half miles on a bike. >> you can tell how much lucas is loving this, right? >> yeah. absolutely. >> he's having a blast. just playing like brothers s