Lack of motivation mostly. I find most programs I could build trivial, unless I am learning a new (non-trivial) concept or making money I don't care to build anything. There are very few areas of PHP I don't know so there is little left to build. By this I mean I could build about anything, not that I know every way to build it. My focus has been very far from PHP since I took a job doing .NET, most of my learning went into that since my experience was rather minimal at the time.

Even when I freelanced I didn't build stuff for fun in PHP, it was a money making tool which I did the best I could in. Back when I ran sites for profit I was always coming up with ways to improve my scripts, but I don't care to do that stuff any more since I always came up with reasonable (but bearable) losses for my time.

For fun, I've always liked low level programming (C++ was my first real language). I know some assembly (although don't use it) and I enjoy reading though the Linux kernel to see how they do things directly with the hardware. I also have been trying to do microchip programming to actually apply my programming to something useful (like a digital clock I would actually use), although haven't had the time to actually research it enough to get into it.

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