At times, particularly in the midst of working on one's thesis, it can be very hard to maintain a positive attitude and stay motivated. Many graduate students suffer from insecurity, anxiety, and oftentimes frustration. First of all, realize that these are normal feelings. Try to find a sympathetic ear -- another graduate student, your advisor, or a friend outside of school. Next, try to identify why you're having trouble and identify concrete steps that you can take to improve the situation. To stay focused and motivated, it often helps to have organized activities to force you to manage your time and to do something every day. Setting up regular meetings with your advisor, attending seminars, or even extracurricular activities such as sports or music can help you to maintain a regular schedule.
Graduate students faced with writting a thesis will often encounter a number of ``immobilizing shoulds'' that, if taken to heart, can result in a form of "thesis paralysis" and keep one from making any noticeable progress. Telling yourself that you should have a great topic, that you should finish in two semesters , that you should work 4, or 8, or 12 hours a day isn't helpful for most people. Be realistic about what you can accomplish, and try to concentrate on giving yourself positive feedback for tasks you do complete, instead of negative feedback for those you don't.
Setting daily, weekly, and monthly goals is a good idea, and works even better if you use a ``buddy system'' where you and another student meet at regular intervals to review your progress. Try to find people to work with: doing research is much easier if you have someone to bounce ideas off of and to give you feedback.
Breaking down any project into smaller pieces is always a good tactic when things seem unmanageable. A master's gives you a chance to learn more about an area, do a smaller research project, and establish working relationships with your advisor and fellow students.
The divide-and-conquer strategy works on a day-to-day level as well. Instead of writing an entire thesis, focus on the goal of writing a chapter, section, or outline. Instead of implementing a large system, break off pieces and implement one module at a time. Identify tasks that you can do in an hour or less; then you can come up with a realistic daily schedule. If you have doubts, don't let them stop you from accomplishing something -- take it one day at a time. Remember, every task you complete gets you closer to finishing.