Ahh, when it is like sailing with the wind, flowing with the river, feeling at peace you know you are on your path.   It means feeling at one with what you are doing. 

So, does it mean if you are in pain or struggle then you are off path?

Even when there is great pain and if you truly do stop and pull yourself and consciousness to the highest point you will know you are at peace with it, then you are on your path.

If you are not at peace within, then you are teetering.  Even when there is pain and torture and worry, if there is peace within, then you are on your path.

It may not be something that you want to do that lies before you.  But if you truly centre your being and feel at peace within and know that it will evolve you will go through and absorb the learning.