I'd be happy to

You usually follow this phrase with a verb. For example: I'd be happy to help you move. You can also use it as a standalone answer. If a boss asks, 'Can you send that email?', you can simply say, I'd be happy to! It works perfectly in emails, face-to-face talks, and over the phone. It makes you sound helpful and professional.

Use it whenever you want to make a good impression. It is perfect for customer service or office meetings. Use it with friends when they ask for a favor that takes some effort. It’s great for first dates to show you are a kind person. It also works well when volunteering for a task at a party, like bringing more ice.

Don't use it if you are actually annoyed by the request. People will hear the sarcasm in your voice! Avoid it for very small, instant things. If someone asks for the salt, just say here you go. Saying I'd be happy to for a salt shaker feels a bit dramatic. Also, don't use it if you are in a huge rush. It implies you have the time to do a good job.

English speakers, especially in the US and UK, value 'performative politeness.' This means we like to show enthusiasm when being helpful. It helps avoid 'social debt.' By saying you are happy to help, the other person feels less guilty for asking. It’s a social lubricant that keeps relationships smooth and friendly.

You might hear I'd be glad to or I'd be more than happy to. The second one adds extra energy to the offer. In very formal settings, you might hear It would be my pleasure. On the casual side, people often just say Happy to help! after the task is already finished.