Free will - Go with the flow or struggle against the flow?

In my thought existence is so humongous; we are nothing as individual when compared with the whole. We are comparable to the grain of sand, floating in a river. The grain of sand has two options--struggle against the flow of river or float freely with joy-- it has freedom to choose. What is Buddha's way? I believe following the strict code of conduct, like the one in monasteries - abstain from natural desires of lust or greed, can't enjoy pleasure even if they are in your reach. It is the way of struggle. It's painful, If enlightenment wasn't there as fruit to be got after this self-torture, no one would even bother to become a monk. While the way of Zen -- which isn't independent from Buddhism -- is certainly of another kind, to go with the flow it's joyous ride. Out of them which way did Buddha preferred? Do modern Buddhists have any common opinion about it?