HN: How can I make my brain/mind sharp again?
When I was a undergrad my mind was really sharp, I was clever and great at solving programming problems.  Though it now has been about a year since graduation, and while doing other non programming work my mind has gone cloudy.  I know it sounds funny, but it feels like their is fog or sand up there.  Even looking back at past clever solutions I made, today I don't really even understand them.  It's as if there is a mental block there, as if the nerve routing goes to the right place, but the signals just cant make it.<p>How can I get my mind sharp again and fast?  What are some good but difficult problems, which will keep me interested but also work the heck out of my mind?