OP, some context would be better than a generic vague person yelling at you. Family, girlfriend, plate, friend, boss?

Context is very helpful on here

Sometimes people will yell at you.

The question you have to ask is: "are they right?"

If they're right, stay calm and address their concern. Make it clear that they're right, but that you won't be addressed in that manner. If they continue, end the conversation. Yelling people quickly run out of steam when they realize you aren't listening.

If they're wrong, ignore them. If you can, just walk away like they don't matter.

Need more info

I think you have taken the first step which is self awareness.

You need to expand your comfort zone. You need to train your fortitude by small steps, accepting there will be failures but not aiming too high and so making too many failures.

Sergeants yell at recruits to make them tougher. The enemy will do a lot worse than yell at them, they need to be able to deal with negativety and carry on. You need to get something like this into your life.

Make sure you challenge yourself and challenge yourself to interact. Ideas like a martial art might help or the army as a reservist or some hobby that needs courage.

When in these situations try to view them from the outside not from the rabbit in the headlights approach. say "this guy is yelling at me, now what shall I do about it?" not "Oh shit I am in the shit" Focus on what you can feel -like the ground under your feet, the air on your face not the fear in your head and the adrenaline in your blood. Try to engage in a non retaliatory but non submissive way at first just to get familiar with functioning in this situation. Ask things like "why are you shouting, could you explain that to me quietly please?" Try to talk through it with them. step back or step away if you feel you are losing it. You will fail a lot before you succeed.

Its all training.

Developing good debating skills is essential in maintaining frame. However, willingness to walk away always prevails, which comes from detachment to emotional responses.

Things I recommend:

1. Meditation (you'll learn self awareness & ability to be calm in stressful situations through bigger picture thinking)

2. Gym. Work hard at it and push yourself to get better. This develops mental discipline.

3. Fighting skills (MMA, boxing, kickboxing). Good for when you can't resolve a confrontation/conflict. Necessary for full confidence in self.

4. Develop a passion or find your purpose for being born. This will have you/your passion as your mental point of origin by default.

By telling yourself the truth always (ex. skipped gym because I was lazy & I REALLY COULD OF IF I FOUND A WAY), you are able to see through people's excuses and BS. This allows you immense power in social situations.

A combination of working hard & studying. RP is about self improvement & building self power.

Some of you guys need to stop being such retards in the comments.

Listen up, this is how you handle a situation like this:

-It all depends on the tone and the situation. Sometimes you get some asshole who comes at you with no reason. Maybe they have some pent-up anger against you and they start yelling like a madman. You don't have to do anything. Just stay cool and act like you don't give a shit about them. (Don't be a pussy and freeze up or apologize lol) Just look at them and talk to them like you would talk to a child (and if they continue tell them to shut the fuck up). Or look at them and go on with what you were doing. This shows them that you are not intimidated and scared of them.

-In your case, if the lifeguard is being a asshole, you have to give it back to him. When he says something, just call him out on it. When he tells you to move, you'll say for ex. " what do you mean???! I almost drowned. I'm trying to recover.." And then when he tries to say something, keep pushing him and make him feel like he messed up. You have to look serious, calm and pissed off at the same time, like you are not going to take his shit anymore. You have to be calm and in control, and ask him a lot of questions. This will make him feel guilty and most of the time they will say sorry or they will say they didn't mean it etc... If you have any other questions, let me know.