How to Motivate yourself for studies?

I understand we all go through down phase from time to time, where our hard work seems to be failed. We start looking at ourselves as failures due to situations, and rough times. Let yourself be sad for a while and stay upset. Start thinking now, do you deserve this?
Have you not worked hard enough? you did, if not, work harder. If you did, there is not regret. All minds are not same, and neither they can be. so cheer up ! Keep looking, you will find way in the dark.