Forbearing the opposites is tapasya.

You must have seen that so many saints do very austere penances (tapasya), especially among the Jains. The Jain saints are able to walk bare foot for long distances. They do not feel very cold in the winters or too hot during the summers. They develop a resistance towards extreme climatic conditions because of their tapasya. So this is one of the benefits of doing tapasya. 

But you should not stretch or overdo this at all. Doing too much tapasya and troubling your own body is not advisable at all. It is wrong to do that.

         There are some people who sit with four fires burning all around them and one on top of their head and do meditation. It is called Panchagni tapasya. All this is not necessary. Torturing the body like this is wrong and should not be done. But a little bit of tapasya is necessary. 

         It is said, ‘Tapovai dwandva sahanam’, which means forbearing the opposites is tapasya.

- Gurudev Sri Sri..