What is stopping you from reaching ultimate happiness?

Only myself.

Regrets, bad memories, being confused about who I am/what I believe and getting stressed too easily which then leads to me failing at stuff :)

What's stopping me is, there is no ultimate happiness. Life is all change and transition, the only ultimate to life is death (as far as we know).

My self destructive nature

Addiction.

Doesn't exist

The beating hearts in the chests of my enemies.