The giant reclining Buddha

This statue is enormous -- 45 meters long and 5 meters high. It is at Wat Pho in Bangkok. The temple was constructed around it.
So this is the position the Buddha was in before he attained enlightment, which is to say, before he reached nirvana, which is to say, before he DIED OF STARVATION. Yet he is always smiling. What a contrast to Christianity with Jesus looking pained. Is this reflective of the always-smiling Asian or a reflection of optimism. Or maybe neither.