"O Son of Kunti (Arjuna), the ideas of heat and cold, pleasure and pain, are produced by the contacts of the senses with their objects. Such ideas are limited by a beginning and an end. They are transitory, O Descendant of Bharata (Arjuna); bear them with patience!
O Flower among Men (Arjuna)! he who cannot be ruffled by these (contacts of the senses with their objects), who is calm and even minded during pain and pleasure, he alone is fit to attain everlastingess!"
Paramahansa Yogananda's commentary on the first verse says:
"...The ice on a man's hand is reported to the brain, through the sensory nerves and life force, as a sensation. The mind reacts through perception and reconizes the sensation as "cold". The preconditioned feeling then interprets the sensation as pleasurable or disagreeable, and the body responds accordingly. The coldness of the flesh is material, the cold sensation or perception is purely mental. All experiences of cold and heat, in order to first be cognized as such, must first be converted into mental perceptions. A chloroformed man feels no sensations of cold when a piece of ice is placed on his hand. In short, the mind is the sole power of recognition of any bodily sensation....
...When a cold or hot sensation invades the body, when a pleasure visits or a pain attacks, it tries to overwhelm man's mind with the idea that the sensation has an inherent power of permanence. Aware of this "trick", man should try to adopt a transcendental indifferent attitude in his response to the inroads of all sensations.
When a man adopts a nonexcitable state toward sorrows, a non-attached state toward temporary happiness, a stoicism toward irritans that rouse fear and anger and pain, his minds attains an unruffled state of poise" (pages 201-203).
Difficult to achieve but Wim has showed to us that it is really possible to achieve such a state of mental control. Thanks Wim for the inspiration :-)