Following one's head actually, means acting according to the instructions given by the brain which is inside the head. What is a brain? It is one of the largest and the most complex organs in the human body. It is the center of the nervous system. In simple words, a brain is an organ that controls our thoughts, feelings, memory, etc. Why should we follow our head and not our heart, which is a muscular organ that pumps blood? The head is a hard, strong part of the body whereas the heart is a soft mass. So the decisions taken by the heart will be soft in nature whereas the head's decision will be strong and powerful after careful thinking.
When we have to choose our friends, we have to use our head, think thoroughly, decide whether that person will make a good company and then once decided, then, we can act as our heart says. But a thorough analysis of the person is required. They should not be backstabbers who will deceive us either in the present time or anytime shortly. When we are in pain or trouble, one of the best ways is to talk out our pain to someone close to our heart. But before confiding, think well and only when the person is trustworthy, we should confide in that person. Not only friends, even when talking to a brother/sister, think well before you say anything personal. After all, there is a possibility that the person could deceive us anytime.
When people fall in love, they draw a heart and say from the core of my heart I am saying this, I love you, I will give you my heart or my heart has been stolen, etc. But if we draw a brain picture and say I will give you my brain, how will that be? And this is one of the main reasons for many people having breakups either before marriage or after marriage because they do not think and decide. Especially, love, at first sight, is very tricky. 99% will work out only in films; there is just this possibility that the remaining 1% might click in reality. What if the person is a crook? The entire life gets spoiled. It is always best to think, understand, judge the person, whether he/she will be compatible with you, explore their family background, understand their family culture, creed, etc and then decide whether to choose or not. Haste always makes waste. Any hasty decision made without making proper analyses will end up in misery for both of the couple.
We all have heard about brain drain. Is there a heart drain? No. People born in one country migrate to another country either for studying, working or for research purposes. Thus all brilliant and clever brains get drained to another nation. They go to another nation for studying, then, later on, start working for that country and get settled there permanently. But money earned by them came back to their home country thus the revenue improved even though the brilliant brains were lost totally. But now reverse brain drain is happening, they all are coming back to their hometown, at least 50% of them, to start their businesses. They used their brains and went abroad, again after sometime followed their brains and came back to their country.
Inside our head sits the most powerful organ ever known in the universe. But we have still not used its potentiality completely. Research has been proved that only 10% or less of the brain has been used by a normal brilliant human being. Always keep the brain active, relaxed, and stress-free by going in for yoga, meditation, relaxation techniques, getting professional guidance, etc. to keep the brain active to increase the usage of it. A stress-free brain can do wonders to the human force. So follow what the brain says.
Yes we should follow our head, but it varies from situation to situation.