Dr. Dukkha wrote:
If I believed that this was my only life, I'd be a monk Right Now, and I'm 20. It would be my only goal to reach Nibbana and live a peaceful, fruitful life with no suffering. Or I would truly live life on the edge and enjoy.
Just to build upon what others have already written:
Buddha explained that human form, a type of sentient being, which is capable of discovering, penetrating, understanding, and practicing The Dhamma as he taught it is extremely rare. He likened the odds to that of a blind sea turtle swimming into the sea, diving to the bottom and rising in the middle of the ocean, and, upon surfacing, finding his head and neck in the center of a single collar yoke. Pretty thin odds.
Buddha also pointed out that there are many, many, (.....) many worse opportunities for rebirth.
So, (short version) the idea was to search, discover, learn and practice while we can, as if we were on fire, earnestly looking for a way to end our stay in this sea of dukkha, samsara, a place of searing pain and suffering, while still in this rare form that we currently occupy. Life is short. Time is running out. (tick tock). It may be many eons before we get another shot at it.
Following is an excerpt for your examination:
2. THE DANGERS PERTAINING TO FUTURE LIVES
A. Objective aspect. Our liability to harm and danger does not end with death. From the perspective of the Buddha's teaching the event of death is the prelude to a new birth and thus the potential passageway to still further suffering. The Buddha teaches that all living beings bound by ignorance and craving are subject to rebirth. So long as the basic drive to go on existing stands intact, the individualized current of existence continues on after death, inheriting the impressions and dispositions accumulated in the previous life. There is no soul to transmigrate from one life to the next, but there is an ongoing stream of consciousness which springs up following death in a new form appropriate to its own dominant tendencies.
Rebirth, according to Buddhism, can take place in any of six realms of becoming. The lowest of the six is the hells, regions of severe pain and torment where evil actions receive their due expiation. Then comes the animal kingdom where suffering prevails and brute force is the ruling power. Next is the realm of "hungry ghosts" (petavisaya), shadowy beings afflicted with strong desires they can never satisfy. Above them is the human world, with its familiar balance of happiness and suffering, virtue and evil. Then comes the world of the demi-gods (asuras), titanic beings obsessed by jealousy and ambition. And at the top stands the heavenly worlds inhabited by the devas or gods.
The first three realms of rebirth — the hells, the animal kingdom, and the realm of ghosts — together with the asuras, are called the "evil destinations" (duggati) or "plane of misery" (apayabhumi). They receive these names because of the preponderance of suffering found in them. The human world and the heavenly worlds are called, in contrast, the "happy destinations" (sugati) since they contain a preponderance of happiness. Rebirth in the evil destinations is considered especially unfortunate not only because of the intrinsic suffering they involve, but for another reason as well. Rebirth there is calamitous because escape from the evil destinations is extremely difficult. A fortunate rebirth depends on the performance of meritorious actions, but the beings in the evil destinations find little opportunity to acquire merit; thence the suffering in these realms tends to perpetuate itself in a circle very difficult to break. The Buddha says that if a yoke with a single hole was floating at random on the sea, and a blind turtle living in the sea were to surface once every hundred years — the likelihood of the turtle pushing his neck through the hole in the yoke would be greater than that of a being in the evil destinations regaining human status. For these two reasons — because of their inherent misery and because of the difficulty of escaping from them — rebirth in the evil destinations is a grave danger pertaining to the future life, from which we need protection.
source: http://www.accesstoinsight.org/lib/auth ... el282.html