Here's my vote for skateboarding. You'll never look at boring old stairs, ledges, and curbs the same.

very true. I spent a few years deep diving into manual film photography, scanning and digital printing. I learned to study photographs upside down to see the geometries. The process logic, chemistry and relevant metrics opened my eyes and helped me appreciate fine photography.

Algorithms are really great foundation for learning anything. I prefer outcome goals driving new learning experiences.

My latest project is optimizing a homemade $10/day food regimen optimized for 1) gut immune health, 2) inflammation and 3) common North American seasonal allergies. I call it OSL - Open Source Longevity for retirees. I recently learned Wholefoods gives away premium fish heads for free around 10AM. I have never eaten better cost accounting for homemade tahini, yogurt and peanut butter.