The large amount of pressure and stress from various sources influences our lives in multiple ways. Of course, there is the negative angle that most highlight: stress related health problems, breaking under pressure, etc.
But there is another side to these evils, a positive spin on their existence that proves their presence to be crucial in life. Think of all the aims and aspirations one has during a lifetime, what truly compels us to persevere and achieve our goals? It could be the satisfaction and happiness one experiences on fulfilling their dream, or it could be the fear of being unable to garner one's goals. The apprehension of facing failure that necessitates the need to perform better, the trepidation applies the required pressure that aids us in paving the path to success. Remember that test you wished to ace? The lead in the school play you wished to acquire? Or generally any small or big goal you set for yourself, think about what brought you closer to your target. A simple law of physics states that to bring a change in the body, one must apply a certain degree of force on it. The same statement is applied here, one administers the required pressure to facilitate a change in their current actions, so as to accomplish one's purpose. So we can curse the various forms of pressure  we are under, but these forces are mere facilitators, without whom we would lack the apparatus to be better at all we do.
One requires objectives in life to look forward to, and to be brought closer to their fulfillment provides a sense of accomplishment and happiness like none other. I speak from personal experience : I wished to garner a certain percentage in my midterm examinations this year, while I studied I continuously thought of how this could affect my future: near and distant. I thought of how my grade point average would drop, negatively impacting my college application and hence jeopardizing my chances of getting  I couldn't help it, and finally it was this apprehension that gave me a strong motive to give it my level best. I did apply a lot of unnecessary stress on myself but in the end it was worth it because I fulfilled my ambition and the contentment that followed set me on Cloud 9.
Therefore, stress isn't necessarily evil in every aspect, its positive aspect is clandestine but present none the less, acknowledge the benefits it entails and apply it to every venture in order to perform to your best capabilities!