Many people think of excitement as happiness. They are thinking of something, or expecting something that they consider to be happiness, and for them, that is already happiness. But when you are excited you are not peaceful. True happiness is based on peace.
"The Art of Power"

There is a Vietnamese proverb, "Tri tuc, tien tuc, dai tuc, ha thoi tuc." That means, settling for "good enough" is enough. If we wait until all our needs and wants are met, we may wait forever. "Tri tuc" means "good enough." "Good enough" means being content with the minimum amount necessary. Your shirt and pair of shoes can last another year. It's all right for three or four people to share a desk for studying, there's no need for each to have her own desk. Settling for "good enough" in terms of simple living will bring us contentment, satisfaction, and happiness immediately. As long as we think our lives are not good enough [materially], we will not have happiness. As soon as we realize our lives are good enough, happiness immediately appears. That is the practice of contentment.
In Vietnam there's a school of Buddhism called the Four Gratitudes. Just by practicing gratitude, we can find happiness. We must be grateful to our ancestors, our parents, our teachers, our friends, the Earth, the sky, the trees, the grass, the animals, the soil, the stones. Looking at the sunlight or at the forest, we feel gratitude. Looking at our breakfast, we feel grattitude. When we live in the spirit of gratitude, there will be much happiness in our life. The one who is grateful is the one who has much happiness while the one who is ungrateful will not be able to have happiness.
Two Treasures: Buddhist Teachings on Awakening & True Happiness

...there are various factors that contribute to attaining that level of joy and happiness which we conventionally also recognize as sources of happiness, such as good physical health, ...the wealth that we accumulate, ...and a circle of friends we trust and with whom we can relate emotionally.
Now all of these are, in reality, sources of happiness, but in order for one to be able to fully utilize them with the goal of enjoying a happy and fulfilled life, one's state of mind is crucial. If one harbors hateful thoughts within, or strong or intense anger somewhere deep down, then it ruins one's health, so it destroys one of the factors. Even if one has wonderful possessions, when one is in an intense moment of anger or hatred, one feels like throwing them—breaking them or throwing them away. So there is no guarantee that wealth alone can give one the joy or fulfillment that one seeks. Similarly, when one is in an intense state of anger or hatred, even a very close friend appears somehow "frosty," cold and distant, or quite annoying.
What this indicates is that our state of mind is crucial in determining whether or not we gain joy and happiness. So leaving aside the perspective of Dharma practice, even in worldly terms, in terms of our enjoying a happy day-to-day existence, the greater the level of calmness of our mind, the greater our peace of mind, and the greater our ability to enjoy a happy and joyful life.
Healing Anger: The Power of Patience from a Buddhist Perspective

Happiness is not something ready made. It comes from your own actions.

If you want others to be happy, practice compassion. If you want to be happy, practice compassion.

The purpose of our lives is to be happy.

Question: You often speak about the need for mental peace. What do you mean by it? Does it denote a specific state of mind?
Dalai Lama: Mental peace? If you reduce anger and attachment, you reach a point when your mind always remains calm or stable. It is as simple as that. Strong anger and attachment create waves in your mind. People may not realize when they yield to desire or develop attachment that it will cause them mental unrest. But actually, when a strong desire or attachment occurs, during that moment mental peace is lost. To reduce attachment, especially anger or hatred, leads to mental calmness. This is what we call mental peace.
Q: Isn't it also necessary to practice meditation to obtain mental peace?
DL: My experience is that it is obtained mainly through reasoning. Meditation does not help much.
The main cure is to realize how harmful, how negative, anger is. Once you realize very clearly, very convincingly how negative it is, that realization itself has power to reduce anger. You must see that it always brings unhappiness and trouble. Of course anger comes. Anger is like a friend or relative [whom] you cannot avoid and always have to associate with. When you get to know him you realize that he is difficult and that you have to be careful. Every time you meet that person--still on friendly terms--you take some precaution. As a result the influence that he has over you grows less and less. In the same way you see the anger coming, but you realize "Ah, it always brings trouble, there is not much point to it." The anger will lose its power or force. So with time it gets weaker and weaker.
A Policy of Kindness

Whatever joy there is in this world
All comes from desiring others to be happy,
And whatever suffering there is in this world
All comes from desiring myself to be happy.

If I do not actually exchange my happiness
For the sufferings of others,
I shall not attain the state of Buddhahood
And even in cyclic existence I shall have no joy.

When you have the thought that each being is so precious, then naturally respect comes, then you want to offer service, and if there's anything you can do, even just a small thing you can do, then it makes you so happy, even just a small thing you can offer, it brings incredible joy and happiness, satisfaction and fulfillment, meaning in life.

You don't need to obsess over the attainment of future realizations. As long as you act in the present with as much understanding as you possibly can, you'll realize everlasting peace in no time at all.

If you neglect to protect your mind, you can neither close the door to suffering nor open the door to happiness.