Work is work- You shouldn't expect it to be cheery and fun at all times. That's why you should find a career in what you love so that it won't phase you as much on the other days.
Friends are friends. You shouldn't have to convince a friend to be a friend. They just know what to do and when to do it.
Be who YOU are- That's all that really matters. If the next person doesn't like that or even respect that then that's their loss. You shouldn't have to compromise your beliefs or personality to appease others.
Worrying brings more worries- Try to pray to get through those times that make you anxious and let it go. If you worry too much about things beyond your control, you will make yourself sick which in turn brings more worries.
I hope these few phrases help you in anything that you are going through or getting through. I had to write them out to help me get through a few things that i have been challenging this week. It's all good now!