As has already been stated planing your time so you can get the work required completed by deadlines is important, but you will also need to schedule some fun times too. All work and no play is not a healthy balance.
When under pressure or under stress take a break from the situation causing it and apply some relaxation exercises. When in a relax state where all muscles are relaxed and you have released the tension both physical and mental ask yourself two question:
"Do I have control of the situation?" and "Is there anything I can do to improve the situation to reduce the pressure or stress?"
If the answer is NO in both cases, then learn to let it go. If you doing this in a relaxed state you might be surprised how the answers will come to you on how you can improve the situation. A relaxed brain and body helps clearer thinking.
Hope that helps and don't forget to enjoy the journry you are on.