No, for most people there is a low point in their midlife somewhere, then progressively happier once past that.

I’ve never been as unhappy as an adult, as I was when a child. My least happy adult time was my 30s, and from there it’s been all upward. I’m sure once I am old old there will be health shit to worry about, but for now it’s easier to be happy than it was before, and I have seen research showing that is typical.