Best Resources for Self-Learning Data Science

Hello,

I'm an undergraduate data science student I'm studying the material and I sort of stress over being efficient with my studying because of this I think about what the best resources are a lot. I've been struggling a decent bit with the Math elements of Data Science. Especially with things like the Dual Problem that can be hard to visualize. And also generally want to get better at Programming especially lower level programming. But I'm getting to the point where I feel like I'm getting diminishing returns from reading textbooks and professor lecture slides. Does anyone know of any resources that might be good for generally math elements of DS & programming especially lower level.