Well, I often compare this practice to a mountain hike ... a lifetime hike ...
I have found that, through many years of practice, it is a never ending exploration ... always something new is revealed over time, always another corner or vantage point disclosed. Never ending, something like a long love affair in that way. Always a new surprise, an insight, a discovery awaits ... (and a lot of bumpy times to be surmounted too!)
My friend Nonin likes to say, "A moment of Zazen is a moment of Buddha. But 25 years of Zazen is 25 years of Buddha".
It is also Buddha 25 years more mature.
Of course, any "hike" inevitably will seem like a "lost trudge" sometimes, as if the path is lost. It will not always pass lovely or breathtaking scenery, and sometimes may seem way off course.
We all go through times when it seems "nothing in happening" and we are "getting nowhere" in this practice (and I do not mean in the good Zenny way of "no where to get to" ... I mean that it feels we are at a 'dead end'). Then, suddenly, like drops of rain wearing away a mountain, one realizes that this practice has seeped into one's bones ... slowly, slowly.
There is a certain enthusiasm, trust and energy we must bring into our sitting to make sure that we stay vibrant, and do not turn into just lumps on a log (over the long term, I mean. We all have lumps-on-log days). We may even go through weeks --and months-- when it seems that the practice has lost its way, and we think "there seems to be no point" (and I do not mean a good Zenny way of "there is no point" ... but more "this is pointless"). Fear not! That is the time for trust in the practice.
Stick with it and the tallest mountain will be walked ... step by step, worn away ... drop by drop