Well, money is a strong motivation... especially when there is a serious need for it.

Maybe a project that is not dependent on your knowledge of the language can work for you. I mean one that doesnt challenge how much you know about PHP or the languages that you know but how much you can really think. Why not build something that no one has ever been able to? Well those are just random thoughts... so.

Motivations can vary, but also the feeling of accomplishment at the end among other things.

Just a thought, it makes me think of Rocky 3. When youre at the top already its like theres nothing else to pursue. It sorta leads to you getting rusty since you start taking things lightly and your confidence somehow can get the better of you. Well on the movie Mr. T came along who was maybe not better than Rocky but was just way more determined and motivated and he took the title from Rocky.