For the same reason you don’t always want to have sex.
Or have a beer.
Or eat.
Or sleep.
Or play video games.
There is not a single thing we want to do all the time.
That’s just part of the human condition.
Life is a fluid experience with different desires and fears arising at different times.
This is also the great fear of the human mind that so desperately seeks permanence.
We want certainty and guarantees, something solid we can hang onto in the ever-flowing river of life.
It’s why we have contracts and marriages, and why we cling to symbols, concepts, possessions, and gods.
But not only is all this is desperate, it is futile.
As Alan Watts said, “the only way to make sense out of change is to plunge into it, move with it, and join the dance.”
Notice that all of life is happening for you, not to you.
When you haven’t eaten, the sensation of hunger - the desire for food - spontaneously arises to meet that need.
The same is true for all the other sensations.
Don’t fight them or doubt them.
Relax into them and join the dance.