Crying on cue can be a challenge for many actors, but a lot of emotional scenes require crying. If you're struggling to find a way to bring tears to your character's eyes, try using reverse psychology. Thinking as your character, think to yourself, "I'm not going to cry. No matter what, I won't let them see me cry." In real life, you've probably had an experience when you've tried to holdback tears. Channeling the desire not to cry, despite needing to, can help trigger tears on stage. You can also consider moments that made you cry in the past. If you know you have to cry during a scene, spend some time thinking of sad moments before stepping onto the stage.  It may help to do a free write on the topic of sad moments, jotting down the saddest moments you can recall. This will give you a stockpile of sad memories you can use in the event you need to cry on cue. You do not have to focus solely on your own personal experiences. It may be too stressful to channel personal experiences. Instead, try to think of a moment from a book, movie, or TV show that made you cry. Crying is very much a physical reaction. If you go through the physical motions involved in crying, this may trigger actual tears. Consider what you do when you cry in real life. Maybe you start to breathe heavily, sniffle, and make small sobbing sounds. Start to engage in these actions. You may find that, in response, your body produces tears. If you're really in a bind to make yourself cry, you can look at the stage lights. Bright stage lights may irritate the eyes, resulting in tears. Many professional actors use this trick if they're struggling to cry in a particular scene.
Use reverse psychology. Think of past sad experiences. Go through the physical motions of crying. Use stage lights to trigger tears.