Don't ruin today by worrying about yesterday's problem. Yesterday won't ever come back, just make the best of today.
You will have days of joy, and extreme happiness, and you will have days with mixed emotions, loneliness, and feelings of being lost. You will have days in which you feel that you can do nothing right, and then there are days in which you feel that you can't lose. Every person will have their good days, and every person will have their bad days.