For checking the transcript: https://www.buzzsprout.com/2379282
Stick at sth
means to keep trying or keep working on something, especially when it’s difficult.

Examples:
1- Imagine if Steve Jobs had given up on his ideas after the first failed Apple product. But he stuck at it, and the result? The iPhone!
2- Imagine if Steve Jobs had given up on his ideas after the first failed Apple product. But he stuck at it, and the result? The iPhone!