What I have done when I am in that situation is to take that time to learn and to do something I like very much...
I have read about meditation, I have tried to concentrate more on what I am doing in my every day life activities, even if it is only to wash the dishes, and be there doing that without thinking anything else. Focus on what I am doing and doing it with all my senses. It might be seen as a crazy idea, but when I arrived to the field last week, I could focus more on what I was doing and I could feel a lot more the place I was. Apart from taking the pictures, it was a great personal experience.
Two or three months ago, I start thinking why I didn't go out to take pictures as before, and I found that my fitness was not so good anymore. As a discipline now I walk 7 km 3 or 4 times a week, this to improve my physical condition. I take long walks with a Lady who loves the forest... we walk in different places, and talk about trees, flowers, she tells me how she sees the forest and I share how I see it and what I see... I spend long time only watching the lake, and the birds passing by and trying to get so much in peace. Sometimes I become too worried about my pictures, thinking "All has been done, I can't do anything new, I see my pictures so boring" and feeling very sad about this thought. I learned then that I had to be relaxed and let pass this worry, because that blocks me and take the fun out photography.
I have also seen some videos of John Daido Loori he was a Zen Buddhist monk and a photographer. He explains how you bring your mind to capture that moment... and he talks about "the moment". I watch the video of Andy Goldsworthy with the idea of learning about him and what was moving him to do his art. I didn't take my camera to take pictures after watching all this material, or tried to imitate their pictures. I just planted their ideas and let them there... sure that one day all what I learned from them it will be useful.
And I did all this with no hurry, sure that it would take the time that it was needed... Last week it was my first experience out there after all these months with no pictures and I enjoyed it immensely. Still I think I need more time, more training on focusing.
At the end, I am happy about these periods of lack of motivation because I learn a lot and every time I feel closer to find the way to take pictures and enjoy myself without any pressure.
I hope my experience helps...