What motivates you? If you are having problems getting your research program off the ground, the problem might be one of motivation.

What motivates research? In my particular case there are several factors. Extrinsic considerations like:

(1) Competition. I like the game-like aspect of trying to be better than any else at something.
(2) Prestige. Fame. Institutional status. Rank etc...
(3) Publication. I like seeing my name in print. It is addictive.
(4) Proving my enemies / doubters wrong.

Or more intrinsic factors:

(1) Curiosity. There are many things I would like to more know about. Sometimes I think I'd like to study pragmatics in detail, coming up with original ideas about Grice's conversational maxims. Research provides a focussed channel for curiosity, a control that prevents me from trying to learn about everything all at once.
(2) Self-fashioning: the ability to construct one's own intellectual biography according to an image-ideal.
(3) The opportunity to promote my own interests in the wider world, to showcase my own opinions and perhaps influence the way other people think about subjects I am deeply interested in.
(4) The ability to engage in intellectual dialogue with other smart people.

On the other hand, I'm not very motivated, say, by a political or social agenda (sorry!). I suspect most people's motives are similarly mixed between intrinsic and extrinsic factors. Without extrinsic motivations, people would still pursue their interests, but they would not produce as many publications. Extrinsic motivations, however, don't work very well on their own. If you don't love the work itself, it's hard to do it just in expectations of palpable rewards, many of which might materialize decades later, if then.

Before tenure, getting tenure can be a motivation. Even then, though, I think I was mostly focussed on the competition / publication / proving my enemies wrong factors. I wasn't thinking along the lines of doing enough to get tenure, but instead trying to publish in the best journals and making fools of people who thought I wasn't that good. Academia is a brutally competitive profession, after all.