The real purpose of life

"Im bechukosai teilechu," Hashem says, and Rashi explains it cannot mean keeping the mitzvos, since that comes next. It means toiling in Torah. But chukim are laws we cannot understand, so what is hard to understand about learning, and why "walk"? And how can the prayer at a siyum say that others toil without reward, when every worker is paid? The word "amal" holds the key. A Vilna Gaon mashal of a king, a river and buckets with small holes reveals who understood it.