First which category does your problem fall into? Think about problems as being in two categories.
Permanent Problems These are problems that you have no control over and cannot change. They are issues that you need to learn to deal with. You can't change a permanent problem. So stop wasting your focus and energy on these kinds of problems. Some great examples of permanent problems.
Time. You can't change time. There are always the same 24 hours in a day, 7 days a week and 365 days a year. No matter how much you try, that will never change. So there's no need to focus on the fact that you don't have enough time for something. Focus on time management so that you can make time for those things that ARE important to you.
How Old You Are. Pretty obvious, you can't change your age. Whether you want to be younger or older, this is something that you cannot change.
Past. You can't change the past, so stop dwelling in it.
Family. You can't change your family. You can choose friends and who you share your time with, but you cannot change who your family is.
Other People. This may be a difficult one for a lot of people. But you need to realize that you can't change other people. You may be able to influence some people. But to change a person's hard wiring, that is something only that person can decide if they want to change, not you. So focusing your time and energy into trying to change someone is a complete waste of your time.
Body Shape. If you don't like how much weight you've gained you can do something about this.
Relationship. If you're unhappy in your relationship you can change that.
Work Issues. You hate your boss, you don't like how you're treated. You can change how YOU interact with your boss, or you can even change your job.