Tension can be physical, emotional or mental. Basically, physical tension is that of muscles; emotional tension is of stress hormones; mental tension is of ideas. Mind tension is not necessarily painful, as one can be physically and mentally stressed, yet emotionally happy, in peace with oneself. No wonder many intellectual pleasures and creative works derive from such tension of ideas.
The mind is tensed up by DOUBT, in any form it has, about:
Mind tension is high when the gap is wide between doubt and certainty, dream and reality, fear and trust, diffidence and confidence ... Any pressure by society, physical needs, or TIME, increases such tension, for being uncertain we can bear it or not, without cracking, breaking up ... or dying.
There are many tension control techniques, to ease the tension caused by doubt while benefiting from it as well:
Focus: Just as too much tension exhausts muscles and senses, causing unnecessary pain and disturbance, so does "excessive thinking" to the mind, when we follow ideas abstractly, aimlessly or nervously, without knowing what they refer to, how to process them, and where to apply them.
We need to focus our energy to "minimize and benefit" from such tension. Ironically, focus is an act of mental relaxation, not stress. It's to use minimum voluntary tension to avoid much involuntary one. It saves the thinking energy usually lost in fears, confusion and rambling thoughts.
Mental focus can be achieved initially by simple repetitions and mantras, as well as short physical tension. Then once focus is achieved, one starts arguing with one's fears and causes of tension.
Arguing:. Facing one's doubts is the shortest route to certainty and best medium to eliminate or minimize doubts. Knowing how to argue properly and think logically saves so much time, lost in endless possibilities and scenarios equally battling in our mind.
Relaxation: Tension is painful, yet a timely partial tension is good. To benefit from mind tension, applying it to the right time and place, and safely reach high tension levels for long time without damage (exhaustion, frustration, confusion, or even trauma), we must be equally prepared to loosen up, by mastering mind relaxation too. Flexible shifting between tension and relaxation protects us against the harms of tension while rewarding us with its benefits.