Your life does not begin only at the moment of birth; and death too, does not imply the end of everything. Actually, you existed before you were born, and you will have another life after death. You will be reborn in another place and the cycle of life and death will continue endlessly.
Birth Is not a beginning and death is not an end.
The constant rebirth into this suffering World is a bigger problem than the simple death at the end of each life. Constant rebirth is difficult to solve and it becomes a critical issue when you recognize and wish to overcome it.
When there is birth, there will be death. During this process of life and death, you have to consider your profits and losses. If you do not put in an effort to uplift yourself, you may lose your Human status in the next life, and this will certainly be a loss!
No matter how long you live, once the life that you obtained from your past karma is finished, you will die. It is like a lamp. When the fuel is consumed, the light will go out. If the karmic fuel for your life is for hundred years, then, at the end of hundred years, you will die, and there is no alternative!
Whether you are young or old, you may die at any time. Although Humans have an average life span, exhaustion of merit or unforeseen circumstances for any individual may cause you to die at any time. Life is impermanent. So you should not wait until the next life, or life thereafter!
Do not think or misunderstand that life is determined by your past karma only. In fact, the major influence comes from your actions in the current life. If you always commit wrong deeds, do not take care of yourself, and be lazy, then consequently you may become poor and may die of starvation.