A person from the defence forces is clearly distinguishable in a crowd. We normally attribute it to the rigourous training that these people go through before being ready for combat. It may be partially true, but it is not completely true. The reason is a loss of idenity. It may seem intriguing but, yes its the loss of identity at an early age that shapes up the intangible parts of self, such as the personality that distinguish them from the other civilians. The concept of extended self says that our attachments, i.e. our physical possessions become a part of ourselves. They start from our body parts to closer things such as hair styles, tattoos and move on to cars we own, the people we move around with to the institutes we join to the company we work for. A deep attachment with a possession makes such a possession a part of our-self. As people join defence, all this is stripped off and they are all the same. In a bid to be distinct and differentiate themselves, other facets of their personality shape up in a quick manner, maturing faster than those who still have all those possessions. As years pass by their personalities shape up making them stand out in a crowd of civilians. It is not their original self that allows them to do so, but the sudden loss of their possessions that helps them do so.
It is not the experience that shapes our lives, but the experience of being away from some of our close attachments that helps us grow. India would not have grown the way it did under the shadow of Gandhi. It was the sudden removal of the most valued attachment that helped build India. The same goes for all the entrepreneurs who ended up building multi nationals employing thousands of people world wide. The true growth of their organization came only after the most valued attachment of the organization i.e. the founder relinquished control on it.
Leaders today are big corporations and political parties. Their most valued attachment is the one holding the baton for such organizations who characterizes the extended self for the members of such entities. For them to grow, it would mean time and again passing the baton to new leaders who would again organically show the path of growth. For individuals, it would be relinquishing the attachments that define the identity in the formative years of their life to be leaders tomorrow. It is an ongoing process, but the only unanswered question is "When to let go ?"
You can read more about research on extended self here