What do you think would be the most difficult thing to do in acting?

If you are expected to truly cry with tears running down your face I think that would be very difficult for many people.

Pretending to lose your mind!

Lovemaking scenes.

Faking the belief in what you’re saying.

Making the love.

What @Aster said: crying.

For me, memorization is the most difficult part of acting. With rehearsing, the dynamics of the scene and of the character you are portraying makes emoting come naturally. I have no problem crying actual tears, having become fully involved in my role, however the audience is usually too far from the stage to see tears, so actually crying is not necessary.

During a rehearsal, actors often “break up” and laugh when a deadpan or other emotional expression is required. But with sufficient practice one can usually avoid this happening during a performance. Effective acting requires the actor to be the character present in a “real” situation.

As long as actors are not conscious of the audience (key is never to look at the people in the seats), they will not “break character.” Sometimes actors will blank out and forget what they are supposed to say. Others actors, remaining in character, will be able to ad lib, cover the flub, and provide a link that helps the actor to get back on track. As long as there is no pause in the scene, the audience will never know.

Sneezing.

Crying while making the love.

Showing emotions is not difficult for an actor. That’s what an actor does. The hardest thing, in a long running production, is keeping it fresh. The dialogue can become rote if you don’t watch out. Reactions can become stale and insincere. Each performance has to be as if you haven’t done it 50 times before. The director can help because s/he can see it when the actor can’t.

Lose or gain a lot of weight for a role. Or any other type of method acting.

Changing your appearance for the roll such as shaving your head or having to body build for months before a role.

I did some college and community theater acting when I was younger. I would have no problem altering hair or facial hair styles (shaving, cut hair, grow hair, not shave, etc) for a role. I would probably have no problem body building for a role, but I would probably draw the line at gaining a lot of weight, or otherwise endangering my health for a role.

Another thing I would have a problem is on-the-mouth kiss with another man. I have no problem with touching, hugging, or anything like that; I just have an aversion to the idea of kissing another man.

Apparently, according to actors in interviews, it is the waiting which is the hardest.

A rape scene.

Playing a drunk, lovemaking or comedic roles.

Jakey?

Personally, I can’t cry. That would be the most difficult thing for me to do. Crying actual tears would be next to impossible.

I was once asked to spit on another character during a scene, and it was incredibly difficult at first. Really difficult.

I’ve never had to make love on stage, so I don’t know how I would react to that direction. It would, of course, be staged and no actual intercourse would be taking place. Thinking about it in that light wouldn’t bother me much, but I’ve been on stage for 42 years, so I have few inhibitions about what I would do as a character.

A sex scene with another man/woman if your spouse is the director. (AAAWWWKWWAARRDD)

Definitely crying on cue. I’m not a crier, I could mimic the expressions but no real tears would be falling. This is obvious anyway with many actors/actresses, they get the expression, but you never see any actual tears.

I have to amend my answer above. I have cried on stage, and I’m shocked I forgot it. I cried in the ultimate monologue as Dr. Martin Dysart in Equus. It was a cathartic moment in a distressing play.

Humping Miss Daisy, erm….does this pay real well or what?

Working with a crap director or one who is difficult or who you can’t get on board with for whatever reason.

Comedic timing and laughing.

@digitalimpression I think they must like to watch.

I acted a bit in high school, and I know crying on cue (or being able to cry at all) on stage, in front of the camera, or whatever would not be possible for me.

Being autistic. Like Rain Man.