Motivation is the most important aspect of effective research. Be motivated, excited and engaged in a fledged idea. Scientists need to be able to respire themselves. Be inspired by the pace of progress.
Motivation waxes and wanes over time. Feel the waves and surf on them. Take stock of your progress, routinely and objectively. Set proximal goals, break the project into manageable pieces.
Consider thinking in terms of if-then routines, rather than to fantasize about the future in order to get more done is less time.
Self-motivation can boost the enthusiasm, but it is not the only way. Also collaborator can inspire you to move forward. They can remind you why you were passionate about your project to begin with and be sounding board for your frustrations. If frustrations lie in a lack of confidence in some aspect of your work, simply improve those skills. One way to do this is to ask more experienced colleagues for additional training or helpful tricks. This will overcome self-confidence-related procrastination issues. Even if you just talk with someone and s/he says "That's is very interesting." that can recharge your batteries for at least a few hours.
Focusing on what excites you about the project in the first place can help you get through most tedious parts. Just thinking about the relief you will feel at having that part of the project behind you - and knowing that afterward you will be able to move on to more exciting parts - can give you the boost you need to start a tedious task.
Several different kinds types of positive emotions exists, such as hope, gratitude, awe, and pride. Any of these can motivate someone to become a scientists or to choose some other field.
Where once it was the big ideas that drove you, you might need to look to other aspects of the experience of doing science. Perhaps you can get the same emotional experience from mentoring others [http://sciencecareers.sciencemag.org/career_magazine/previous_issues/articles/2012_12_07/caredit.a1200133].