Hi everyone!
The other day I heard on ESL Podcast this phrases:

"Let's get started..."

And I have a question. Why does he say "Let's get started..." instead of "Let's start..."? Is there any difference between these sentences? Thanks in advance.
"Let's get started " is almost a "set phrase" for beginning a class or activity. There is no difference in meaning with "let's start". It's just an expression that we say very frequently.
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So can I say "Let's get walked" instead of "Let's walk?" If not what others verb like "start" I can use with "Let's get...?"
My best guess is that "Let's get started" is idiomatic.  It's a common phrase, but I can't think of any other verbs that can be used like "start" in that situation.  Here are some other "Let's get ..." phrases that are common:
Let's get going.  Let's get moving.  Let's get ready.  Let's get together.  Let's get to work.  Let's get busy.  Let's get drunk. 
Another similar phrase is "Get ..." as a command, as in "Get to work" or "Get started".  Again, these are idiomatic, and you just have to know them on a case by case basis.  I had never noticed how odd "Let's get started" was until you asked!  
Sorry Konrad, but no, you can't put 'let's get' before any verb. In fact, I can only think of one other 'let's get' phrase at the moment, and that's 'let's get going'.

There is also a phrase 'let's be having you' meaning 'come here' which is an oddity too.
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