Strive to focus on the present. It is after all a gift. The past is history and nothing can change it. The future must still happen and no person can control it.
Dwelling on past negative experiences only makes it harder for you to move forward in your life. Make it a conscious goal to write down something that you are grateful for each day and post it where you can see it. Then repeat it over to yourself every time you begin to think of prior negative experiences. Repeat this as often as needed during your day and you will find that you are leaving negative feelings and thoughts further and further in the past where they will soon be forgotten. ~ Mike Taylor
When you stop complaining about your problems 
If you love someone 
The fragrance of flowers 
The ugliest thing that you have ever seen