The kid stopped at age seven and a few days. The body kept on going. Life kept right on happening.
You can labor to build a business, a relationship, a family, pay off your debts, exercise to keep your body healthy, be timely in all senses, stay abreast of the latest news, play the stock market carefully, save a little with each paycheck; and in an instant it can all be wiped off the map.
You can have power over how you live your life. That is the essence of what is meant by "living in the moment". You aim to soak up all that each instant has to give you. Conscious existence. Deliberate awareness, even when the moment sucks rotten eggs, gives you a keystone when the world around you breaks.
But what happens when you can't trust your mind?
Where does your depression take you?