Collocation! For a stress-free life (and for a higher IELTS score for vocabulary), use one of the following instead:
The rapid pace of modern life is what causes most people to experience stress.
The rapid pace of modern life is what causes most people to suffer stress.
The rapid pace of modern life is what causes most people to suffer from stress.
The rapid pace of modern life is what causes most people to feel stressed.
The rapid pace of modern life is stressful.
Advanced students can consult this comprehensive collocation table for stress.
Above all, try not to become too stressed out by stress.