We should control our emotions. Not to let your emotions run your life is an essential factor to live in a society.
Some people cannot perform this task well. For some of them, I recommend to read this book.
Amazon.com: Don't Let Your Emotions RunYour Life: How Dialectical Behavior Therapy Can Put You in Control (KindleEdition)
This is a textbook written by a therapist of Dialectical Behavior Therapy (DBT) which was established by Dr. Marsha Linerhan. DBT is a package of therapeutic techniques. But this book includes some essence of DBT for easy usage.
On the other hand, it is often said that taking an objective view against self is important. To be objective is similar not to be emotional. But the former is far more difficult. I think that perfect objectiveness is almost impossible for a person.
For instance, a method of “self-monitoring” is sometimes used to be objective. In cognitive therapy, a client is demanded to note his emotion on his diary every day. He records his feeling with a score of 0 to 100 points. When he marks 30, he is depressed. He may feel good when he marks 80. After continuing, the client will be able to know his own emotion. He will also recognize what kind of events makes him depressed.
It is a simple way of meta-cognition.
However, most clients experience a tough time to accomplish it.
There are two obstacles to perform self-monitoring.
First, extremely depressed people cannot perform any tasks. I have experienced a client who seldom wrote a diary. She made a comment only when her mood got better. The empty page of diary meant severe depression of her. As a result, I could know the exact mental state of her to improve her condition.
The other is cognitive bias. We tend to overestimate our feeling. When you are depressed, the circumstance around you looks like a terrible situation. It hurts you so seriously, that you will be more disappointed. A beginner of self-monitoring often marks only either 0 or 100 as his score of mood. To be sensible for minor happiness is difficult for depressed patients.
Therefore, I do not recommend you take an objective view on your mind.
Instead, you should have reliable friends or family members who are sensible for your feeling. And obey their advice. It is more effective for you to keep your mind functional than self-monitoring.
You never notice your own mind. Unfortunately, it is a human nature.