A while back, I ran a poll here on JavaLobby to find out why people became software developers. The answers were varied, from computer science being a convenient choice, to money. But the most common themes were that developers "knew" that it was right for them when they started writing programs, and that people were interested and excited by the future of technology.
Developing software is fairly addictive: you start with a blank file, and at the end you have something that at the end is (probably) useful at the very least, and possibly brilliant at the other extreme.
The amount of change in the industry is fascinating. From acquisitions, to new frameworks, new programming languages and new technologies, developers are never bored.
I definitely believe that right now is a great time to be a software developer. The range of devices that are available to us to create application is astounding. And this is what motivates me most right now - that almost any idea I have can be implemented thank to mobile devices, and people being connected to the internet 24-7. As well as developing for these devices (iPhone and iPad), I love using these devices and seeing what other people are doing. Some applications are amazing, but quite simple, such as FlipBoard. Is there any reason I couldn't do it? Probably not. Keeping up with my peers and having the opportunity to create great applications really motivates me.
I'd like to see what makes other developers tick. Why are you still developing software?