My way of motivating myself to take more and better photos works fine with me, but may not work as good for you. Try it out, or make your own twist of it. I work from a few ideas that I´ll explain further down;

1: Challenge yourself
Set yourself a task and force yourself to finish it. Some weekends I set myself a project that I have to finish. Giving me a deadline and a theme, i.e. Take three pictures illustrating joy. I then try to force my head into coming up with ideas to make it come into the "creative zone". The project can be a short term one or a more long term.

Right now I´m planning a photoseries called "Hired Gun". It started out as a "challenge" from a friend of mine. And now I have three pictures planned out. So it works for me!
If you cant come up with anything yourself, let someone else challenge you.

Another way to challenge yourself is to look up some of the best pictures here on dA and try to make yourself wonder how they have been able to achieve the results they´ve gotten. I often do this to learn more about light or simply to gain ideas.

2: Limit yourself
Going out to take photos is a lot easier when you are restricted to a certain idea. Try limiting your possibilities. Sometimes when I go out to get some pictures I bring only one lens, i.e. the 50mm to force myself to see things in that precise perspective. You can also limit yourself to black and white pictures, a certain angle or anything you can come up with.

3: Evaluate yourself
Be honest when you look through your pictures coming back. A lot of the problem here on dA in my opinion is that people don´t limit what they put out. Anything goes sort of. Look at your photo from the viewers perspective and try to see what you can make better and what you think worked. Evaluating your pictures will make you more aware of flaws in your pictures, after some time these things will annoy you to the point where your brain has learned not to make the same mistake when photographing

Also, all the positive feedback you can get on a photo can never match the criticism you might recieve. In the beginning I hated when people pointed at mistakes I made and what could be done a whole lot better, but now I really want people to give me more of these. The random "OMG THIS IS SO FRIGGING AWESOME" doesnt help a bit. So what I try to do is to pay ten times the attention to the feedback I get on how to improve rather than just the praise. I think this helps me grow as a artist.

Of course, one should always apreciate it if people like your art, its just seeing past this and try to ask yourself if that person is better than you. If so, you have done something right I.e. my grandmother would probably think that all my pictures are great, although I know for a fact that thats not really the reality. My friends that are doing photography would probably not agree with my grandmother, but may prove to be a much better source to look for feedback. That being said, I show my art to my grandmother too No problem being proud of what you do and bask in the compliments from time to time

4: Inspire yourself
Your brain thinks through thousands of ideas each week. I sometimes have this great idea at a point, but forget it really fast again. So I tend to write it down every time that I get a "ideaflash". I find that this also makes it a little easier to begin working on the idea, as I have already started writing about it. If you try to write down a picture in your head, there is no way that can be captured in one line alone. Start writing details of your idea down, and voila, you have an almost finished recipe for your dreamphoto