Most important thing i ever learned was Not to worry about anything i couldn't control,
seems simple enough.... but yet people seem to struggle with this everyday and sometimes dont even realize they are doing it. The other thing was To realize how much control you really have'

Both  are very important to have balance in life, happiness, and true inner peace, once you have those basics down, finding zen in every other aspect of your life is much easier,

To give a great example, When girlfriends or boyfriends spend time worrying about what there significant other is doing or feeling. You can't control if your significant other is cheating, lying, happy, or sad, not there are things you can control which is the second part but for now were gonna discuss the first part. Trying to control other people, or worrying about how other people act is ridiculous, you may as well worry about the weather because you have about as much control over other people as you do in changing the weather.
You can only control you, if you feel an issue is arrising you can control asking whats wrong? but if they dont choose to share with you that is there choice to make.
People spend too many hours worrying about things they will never be able to change.
Now Only worrying about what you do isn't easy and takes years of practicing, and training the mind, but NOTHING worthwhile is easy, and if you use these techniques within a year your way of thinking will change naturally, Fake it til you make it :D

When an issue arrises think first:

1. What role do i play in this?
2. Can i change this? 
3. Will worrying about this make the situation better? 

Example: Best friend cancels to go to movies with you last minuete, says she's not feeling well and you took the night off work for this movie night. Now some people would get upset start wondering if there something wrong with them? build stories in there head like "she's just too lazy" "she just doesn't care enough", "she is a bad friend" or even "she prob is going out with other people tonight! who stays home on friday."

All this up there is making up stories, stories in your head with no fact, evidence, and all of them seem to be hurtful only to you.
Now for the Rules: lets try them

1. I'm her friend, now i can make two choices in this i can decide she is lying and therefore stop talking to someone who would lie to me, and make the choice to stop being her friend. Or i can believe her, what if she's home puking her guts out? or has major diarrhea, maybe her sinus are so clogged she can't breath and is sitting in bed with nyquil, tissues, and soup. Either one of those options are yours to make, and the one you choose you stick to and move on (Never Dwell in the Past, it will only lead you dark places) *discuss that another time.

2. No i can't, shes sick, What i CAN do is call someone else and plan my night, see if she wants me to come over and take care of her, or plan a lovely night by myself working on one of those 100 of things i said i would do if i ever got a night alone.

3. Worrying about her and weather she lied to me or not will not help anything, will only make my mind run with wild stories, and will only hurt me so no need to think about it twice, when it pops in the head with those crazy ideas FIGHT IT....your mind can be a dangerous place, tell it "Shut up, shes a good friend and those ideas are silly and with NO PROOF"....or "yeah so she's a liar i wont talk to her anymore and to move on with my night,"

Now with any situation, Work, Social, spiritual, anything think these steps before letting your mind lead you down a dangerous path.

Sadly we can't trust our own minds, the mind of an addict craves the drugs even if destroys there life, and the mind of a diabetic craves the sugar even if there gonna die, the mind of someone racist tells them to hate based on color of skin, --- You can't always trust your mind, but you can trust facts, looking at the evidence, and if you are lucky enough build a support system of people who as a collective you can trust.