Stress less until you're stressless. When we are under stress, it can be hard for us to develop creative solutions. You're in fight-or-flight mode, engaging your basest instincts. Unless you're Leonardo da Vinci, your basest instincts preclude being very creative.
Is stress ever helpful? It can be. A little bit of stress can make you concentrate. A little more stress can get some adrenaline pumping.
But don't let stress ever be your baseline state. The more stress you start off with, the less excess capacity you have to handle stress when things go wrong (and things will go wrong!)