Life Stream

I have been thinking a lot about flow. It seems to be that there are two main schools of thought on this issue.

I've heard it said that, when things come easily, it's meant to be. And, when they don't, it's not.

Then, there are those who say:

"If you want to accomplish something and the road is rough, those obstacles are the universe's way to see just how badly you want whatever it is you want."

If the second statement is true, just how long is the struggle supposed to last before one decides that enough is enough - time to re-group/re-evaluate and move on?

Any thoughts on this one?