do we really avoid going to shrinks? Sadly, we go to shrinks with matters with which we should go to friends or priests or shamans.

It's not just matter the drugs have side effects, it's that Prozac for spiritual/existential crisis is as useful as vodka or weed.
As much as excercise is good, you cannot excercise yourself out of matters of spiritual and existential realm.

As I said before, it's only recently when death has become such tabboo to talk or think. I do think that OP's problem is not "brain chemistry" or whatnot.