You can sit there forever, lamenting about how bad you've been, feeling guilty until you die, and not one tiny slice of that guilt will do anything to change a single thing in the past. Forgive yourself, then MOVE ON!
We are in a survival mentality, and that's hard-wired into our humanity, because we are the winners of an evolutionary struggle of millions and millions and millions of years.
I like to challenge hitters with a 'Here it is, hit it,' mentality. It's definitely a big part of my game, especially when I get in situations where I need it. I usually save a little bit so it's there for me.
A warrior takes his lot, whatever it may be, and accepts it in ultimate humbleness. He accepts in humbleness what he is, not as a grounds for regret but as a living challenge.
If your message to the universe is gimme, gimme, gimme, the universe's response back to that kind of mentality is exactly the same. The universe will say right back to you over and over again, gimme, gimme, gimme. If you shift that and you say to the universe, to the world, how may I serve? How may I serve? The universe's response back to you is how may I serve you? How may I serve you?