If you've seen all the seasons of The Walking Dead you've probably noticed that Rick's personality changed throughout the series.

Now I have seen all the seasons and I'd like to know what the main "turning points" were, that made Rick the man he is at the end of season 5.

Of course I have seen all episodes, but I can't remember a lot of things that happened in the earlier seasons (because, you know, 5 years). So if someone could point out some major events that define his actions and personality, that would be great :).