"Who needs memories?" and "I'm built upon the small things I do everyday" both seem like powerful tools to gain the 'freedom' that gives us the 'strength' to do our best. I think Hq exemplifies that and ultimately tells us to embrace the present.

"Who needs memories?" urges us to focus on the now and not dwell on past mistakes.
Kageyama seems to embody this struggle. He's trapped by past middle school memories and fear of abandonment. After recrowning and NT camp, he's set free from those memories. +

Letting go of his past gave him the freedom to play at his true strength and in turn, lend that strength to his spikers by giving them the best possible tosses.
This teaches us to let go of the past. But what about the future?

This is where "I'm built upon the small things I do everyday and the results are no more than a byproduct of that" comes into play. I understand this as a reassurance. You've done all you can, now focus on the present and don't worry about the future.

Don't have expectations or worry about results
Ex.Akaashi is trapped by the fear of losing and he spirals in self doubt and pressurises himself, which affects his play. With the help of his teammates & Bokuto , he is set free and finds strength to focus on the present

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Hirugami encompasses both struggles, he beats himself up about the past and worries about his future as a player. He's trapped by both his past mistakes and future expectations. Because of this mental jail that he created, he loses the strength to even play volleyball.

Hoshiumi helps break him out and as he says "All my shackles are gone" we can see he is free from both the burden of past mistakes and future expectations which ultimately leads to the strength that enables him to play his best volleyball.

This whole thing is just a reminder to not beat yourself up about mistakes you've done in the past( you don't need memories) or burden yourself with future expectations and worry about results( The results are just a byproduct of everyday things). Do what you can in this moment.

Freeing ourselves from this mental trap can give us a lot of strength to not only do things better but also find HAPPINESS. Which is the most important. So thank you hq for teaching me that.