https://adventofcode.com/

Here are the things I have done to enhance my own critical thinking:

1. I joined the military and became an officer. You are given business problems to solve in short time with many limitations and adverse conditions. Have fun with that.

2. I write my own software as low as the given language allows. Yes, this is reinventing a wheel, but I tend to get a much more portable solution that typically executes faster with low overhead for maintenance.

3. Become self-sufficient and then invention automation to make that self-sufficiency more automated. The way I think about this is that its not about making money, but instead reducing your expenses to almost 0 and simultaneously taking your time back.