POSITIVE PSYCHOLOGY
Stress
Stop stressing about stressing! Health Psychologist Kelly McGonigal explains that stress only hurts you if you see it as an enemy. If you see stress as a natural mechanism that gives you what you need to cope, then it is not harmful for your health. See her full explanation of how to approach stress, and the physical benefits of reaching out for the support of / to support others around you here:

Mindset
Here is some advice from lifehack.org on what makes people mentally strong.