Ha. What a hubristic title. But it's true. I know a secret. Well, it's not really a secret. The story has been told a googolplex of times. But, I have this feeling that we are afraid to talk about it plainly. So I want to take a stab at it.
The secret is... Pain.
I know, you just had a weird reaction. Kind of like "duh," and "oh shit, I don't want to hear/talk about this." Maybe I am reading into humanity too much, or maybe not, but this is what I see.
There's a problem though. When I say say pain, it's likely not the definition you have. You might be thinking of a broken bone, or an abusive relative, or when you were spanked as a child, or your illness, or your broken marriage. These are not the kinds of pain I speak of. Though, they may become tools for what I am talking about if a person is mindful enough.
I am talking about the pain of service, submission, surrender. Letting go.
Being a bible scholar of sorts, the story that comes to mind is when Jesus washed the disciples feet. I can see the unpolished third world home made of bricks and stone where his knees would touch the stone and rub uncomfortably as he served those who thought he was too good for such a task.
He knew better. To stoop down and suffer a bit in order to lift another above, well, Jesus knew, by doing that, he was in full union with the flow of the Universe, or as he said, God's Will. He was teaching his disciples and us the secret of life. Surrendering to our own suffering for another's benefit without judgement.
It's not easy. It is, in fact, the most difficult thing a human being can do. But it is our main task. To learn to accept pain as the price of surrendering our ego in service of others.
Some might call it sacrifice. I don't think so. I think it is called mercy, and grace. As it was said, "I desire mercy, not sacrifice." This was a pretty incredible distinction, as mercy and sacrifice have been touted throughout history as the same thing. They aren't. The sacrifice spoken of was literal. Blood shed on an altar to atone for sin. But that isn't our mission. We don't have to atone. That part is done. Now, our job is too execute the atonement in our lives through mercy. Mercy comes through service and submission and surrender.
By living these things properly, we attain glimpses of true joy. True joy just so happens to be what we mean when we say we want to be happy.
The next time we get the opportunity, let's surrender our ego and put others before ourselves and cheer as they are lifted on our shoulders to great heights. As you already know, it's worth it.