​​How do Actors/Actresses make themselves cry for a scene?

Physically producing genuine tears is one of the most difficult challenges for actors, especially those who perform live on stage. Actors use a variety of ways to elicit tears.
Different actors achieve tears in different ways, and the same actor might use one or a combination of methods to achieve tears depending on where they are and what they’re trying to bring to their performance.
There is a product called a tear stick or menthol stick. It is a stick of wax packaged in a standard lipstick tube with the key ingredient of menthol — the same thing that creates the cold sensation in cough drops and breath mints. When the actor or makeup artist puts a streak of wax close to the eye, the eyes water, giving the flood of tears the actor can then use as part of the performance.
A more complicated device called a tear puffer or tear blower is a small, hand-held cylinder that shoots a single puff of menthol-laden air into the actor’s eye. The clear plastic tube is spring-loaded and held in the cocked position until the actor triggers it. The puff creates instant tears in the affected eye. The skills required for this illusion is the ability to hide the device from the camera or audience and to puff both eyes at the same time.