Not for persons having heart trouble
Breathe out and shape your lips like the beak of a crow and breath in. Inflate your abdomen, lungs and cheeks. Close your eyes. Touch your throat with the chin. Hold your breathe in with Mulbandha. Then raise up your head and breathe out through the nostrils. This increases the heat of the body. This exercise is not to be practised in summer.
Repeat it three or four times in the winter.