One thing that strikes me is, joy and happiness are things that seem to become more fleeting as one gets older.

There's a James Caan movie where he meets up with his former high school basketball coach, who is old and grizzled, and the coach says something like, "you can't understand the tastes of an old man. No matter what you eat, nothing tastes good anymore."

I don't think any person our age (middle age plus) regularly experiences the overwhelming, exuberant joy we did in our youth (understanding that you've mentioned you didn't have it then, either.)

Maybe a more realistic goal would be to seek a state of contentment.

Also, could it be that maybe part of your resistance in getting to a better spot emotionally is an overall feeling of resentment toward the powers-that-be, toward providence, that you did not receive an exuberant, joyful youth? That perhaps you feel it was a one-shot chance that has come and gone?

If so, that is quite a load to bear. And if so, I would imagine that forgiving yourself or whomever for that may allow you to move forward in a more positive way.

None of us here who know your story can deny that you made fabulous use of your time in your youth (Harvard Law Grad!)

I would say you made some very wise choices throughout your life.
You will always have the means to write your own ticket any way you want.

But I would assess that you have a lot of forgiving to do to get rid of that chip on your shoulder.