You cannot take two breaths at the same time. So also you cannot live two moments at the same time. The problem is that because of the natural tendency of the human mind to get attached to and cling to things, thoughts and people, the human mind tends to worry about and carry all the burdens of the future and cling to the memory of successes, failures and missed opportunities of the past within it. This is one reason why many, if not most people, cannot live consciously in every moment. 

Most people are not even conscious of the moments as they fly by and so are unable to live in the moment. They struggle through the day and get lost in the temporary and illusory world of senses which is constantly changing. Thus they experience a lifeless existence. Instead of fighting the negative tendencies within themselves, they fight with others. Thus, they make themselves and others miserable.

No wonder many, if not most, people are unhappy and strive to escape from their condition through various popular forms of entertainment. 

Life is lived one breath at a time and in each moment. Life begins with the first breath taken in the first moment of life and ends when the last breath is exhaled in the last moment of life on this physical plane.

The past is dead. It exists only in memory. The future never arrives. It exists only in the mind which anticipates it. Only the present is. Life passes us by because we cling to the past and worry about the future. Thus we experience a lifeless existence in the present.

Learn to live in the Eternal Present. You cannot change the natural tendency of your mind but if you develop the ability to be conscious of every breath and every moment then you will feel alive and act accordingly. 

Practicing the various sets of spiritual principles revealed by God through Dr. Dinshah K. Mehta will enable you to reach this state of being.