Pain and suffering
Pain seems to be an unavoidable part of life; Mental stress is your reaction to this pain.
The Buddha said that if you get shot by an arrow, it causes pain. If you get angry, this is a second pain. The wise person stops at the first pain.
In modern terminology we might distinguish between physical (or mental) pain and neurotic suffering. If your head hurts, this is physical pain. If you feel anger, envy or depression, you could call this mental pain. Because of the constitution of our bodies and minds, physical and mental pain occur during life. However, If you ate or drank too much and are worried that your head might hurt later, this is neurotic suffering. It does not stem from reality, what is happening, but from what you think (what might happen).
By learning to better differentiate between reality, what is actually happening, now, and neurotic suffering, the neurotic suffering ceases to appear.
If your head hurts, it hurts. If not, not. That is all.
Sit in a quiet, comfortable, pleasant place.
Listen to the sounds.
Notice what you see.
Become aware of the sensations in your body, the air going in and out.
Watch your thoughts and emotions as they appear and pass.
All this is happening.
But what you think is not happening. It is your creativity.
Distinguish between them as much as you can.