H.H. Penor Rinpoche
This precious human birth, when we have all this intellectual understanding, we have to really contemplate and think about what is the best benefit that one can really achieve within this lifetime. We could just complete our worldly activities. But that is still just cultivating the same kinds of causes and conditions, and we will just rebind into Samsara again.
We will not achieve the ultimate happiness. Even if we have really high rank or we have all kinds of luxuries and material belongings, or we have fame and very good friends and many subjects or attendants, still there is no real essence there from which we can benefit.
So if we spend our whole lifetime just to get success still we will find there is nothing there that we can rely on. Everything is so impermanent and changeable.