Mental health means having a strong mind. The mind should be the servant of the Self. The mind should work for us, not against us. The mind is vulnerable to negative self-talk, what we call ‘tearing thoughts.’ Tearing thoughts arise from negative thinking and feeling like fear, sadness or anger. Tearing thoughts appear when we imagine that other people think badly of us, or when we are hating ourselves. We cannot have a strong mind when we are a victim of self-concern.

On talking about cultivating a strong mind the great yogi Patanjali says (Yoga sutras 1.2):

Yoga (i.e. meditation) is the effort to still the thought and feeling waves of the mind.

Mental health means that we have learned the inner skills needed to quiet the mind when it is agitated. To do this we must turn toward the mind and investigate the cause, recognise the feeling and uplift the feeling by understanding.

In his book Happy For No Good Reason, Swami Shankarananda writes:

Meditation is a method of quietening the mind and experiencing our deepest nature, the Self. The value of experiencing the Self is incalculable. It is an awakening, an upwelling of energy, joy and wisdom. There are a number of ways that this awakening takes place. It can even happen spontaneously for no apparent reason. (Happy For No Good Reason page 34)

To develop a strong mind Swamiji says:

What is the relationship between the outer world and the inner world? The conventional understanding is that the inner world is decisively affected by events in the outer world. When our life goes well we are happy. When our life goes badly we are unhappy. So we try to control events, which we can do only to a limited degree. Hence, we are significantly disempowered, and our moods go up and down when events prove to be beyond our control. In addition, there is inevitable loss due to disease, old age and death.

Certainly, outer events affect us. But by working on our inner world we can develop such strength and independence that we can always return to peace or happiness, no matter what happens. We may be happy when we get what we want, but we can also be happy when we don’t get what we want. I call this condition of inner independence true empowerment. Meditation is an important means to this goal. (Happy For No Good Reason page 41)

Swamiji tells us that meditation is to care about the condition of our inner world. Even though we cannot always achieve what we want, we can be happy even if we do not get what we want. And so, to meditate, to know the Self, to experience the Self, is true mental health.