How might we reduce our good fortune? By taking more than we need and by not using all that we have taken.
Why do we need to conserve it for the end of our lives? Our last moments lead to our next lifetime. To die without pain or suffering, to be clear minded and aware of what is happening is very rare. To be with loved ones and friends who encourage and support us, and to die in an environment where our final wishes are honored is also very rare. To die peacefully enables us to have the thoughts that will lead to a good rebirth.
Whether our wish is to go to heaven or the Pure Land, a peaceful death in which our mind is clear and at ease is essential. And to have all the right conditions to bring this about, we need that good fortune.
Not knowing how much we have or when we will die, conserving our good fortune and not squandering it is our best hope for having it when we really need it.