As mentioned previously, the impact of stress can vary according to our perceptions: but how can that extra “tension” be useful? It turns out we need stress to grow. We all kind of know this, but when stress is happening to us that knowledge can desert us.
Our natural preference is for relief and pleasure. For example, food and sex keep the body’s needs in balance and restore our psychic normality. However, while pleasure is an important part of life’s quality, it does not bring happiness or a sense of contentment.
Our tendency towards relief creates a negative entropy or empty state that feels like disorder to consciousness, which might result in boredom or worry. This, of course, often has us seek relief in the form of some kind of escape from that state; think alcohol for example or more pleasure!
Pleasure/escape may ensue to avoid this unwanted state and “Eventually when you numb it (stress) out enough, you can imagine that you’re happy. You are only happy because you numbed out a huge part of your reality. Which is to say that you’re not really living life to the fullest at all.” 
Pleasure is not Happiness
It depends on what we want from our lives as to whether stress can be beneficial but simply seeking pleasure is not the way to grow; it doesn't address underlying problems, it doesn't add a sense of assurance or satisfaction.
“Pleasure helps to maintains order but can’t create new order in consciousness.” 
We don’t grow as a result of pleasurable experiences
Happiness requires that we develop ourselves i.e., grow
Alternatively, applying or building skills provide the brain with direction gives us relief in a sense and removes the need for an escape. To do that we need to challenge ourselves psychically similarly to physically challenging ourselves in the gym; we push outside our normal state and grow as a result. To do this is uncomfortable to stressful, but if we can learn from our stress or how to make it manageable growth, increased competence and enhanced satisfaction with self can be the result.
To develop greater sense and satisfaction of self (as Henry Ford put it) we need to invest our attention and energy, which we are initially reluctant to make as this is not in line with our natural tendency to the status quo and conservation.
None of this is achieved without the appropriate skills.
Awareness and control over our attention becomes the crucial determinant as this decides where our energy goes, determines if we can tolerate the discomfort of change and growth and whether we can attain those optimal experiences of flow.  Mindfulness helps as the skill of directing your attention is its raison d’etre, and teaches us to be present to our situation rather than be distracted by it.
Nor can stress be overcome and growth achieved while anchored to an unconscious belief system that undermines our potential and dictates our responses to stress, life and opportunity.
Awareness followed by a willingness to learn about our inner self - however inconvenient or stressful; advances the benefit that you get to live your best life.
 Maté, Gabor. When the Body Says No. Scribe Publications Pty Ltd. Kindle Edition.
 Csikszentmihalyi, Mihaly. Flow: The Psychology of Optimal Experience. New York: Harper & Row, 1990. Print.