I suggest that you involve him in your daily routines. Openingly expressing satisfaction and pleasure at the completion of important jobs. I might, also, reward myself (and my helper) with something special (reading time together, food, play time, a walk, etc.).
Explaining that everyone has responsibilities, and as a bigger boy (girl) these are some of his. Taking pride in one's accomplishments is a huge incentive. Don't forget to say thank you. Heck, he might even thank you for all the things he sees you doing. Wouldn't that be something?