The NBA star told media members on the scene that he was able to deliver inspiring messages too ... saying he told the group, "Keep pushing. Every day isn't going to be perfect. We all have bad days. We all have days where it's not great. We're human."
Harden added, "And as long as they can get that at a young age and keep pushing and keep fighting and stay focused on school and taking care of their families, good things will happen."
Publicolor’s founder Ruth Lande Shuman praised Harden for coming out ... while the org. also tweeted a giant thank you to the Nets guard for showing up.
"We had such a great time with you today!" Publicolor officials said. "Thank you so much for helping us transform PS 149 in Harlem!