My PM: I don't like when you get up and help out other colleagues with their problems on their computer. You're not at their service.
Me: okay, I'll refrain from doing so.

The next day, I arrive 5 minutes before 8, I get myself a coffee, talk with a few colleagues, and:
PM: Hey, can you please come and help me review this email?
Me: ** fuck it, I still have 2 minutes ** Yeah I'm coming
PM: Now please.
Me: ...

Also my PM, 5 minutes later: Hey I don't manage to print my document, can you help me?
Me: ...

10 minutes later, I get a call:
PM: did you call XY about ZX?
Me: Yep, sent you a mail about it 2 minutes ago
PM: Really? I don't see it
Me: I sent it.
PM: Can you send it again?
Me: ...

Later that day:
PM: Hey, what are you up to?
Me: Well, I'm working on our improved websi-
PM: Can you please create a new campaign on Mailchimp? We're all under water here and a bit of cooperation from you would be great
Me: ** huh? ** erm, ok?
PM: Do it now
Me: Yeah yeah, don't worry. ** click ** here, done. Now, where was I...

----- PM on holidays

Other colleague from another department: Hey Phlisg! I have a small problem on our platform, can you help me?
Me: ** writes a script to help her out **
Her: awesome, thank you!!
Her own PM, 5 minutes later: Hey! Thank you very much for your help, it helps us out a real lot, very much appreciated :)

I lost my smile at work since the beginning of the year, but that little help I gave my colleague just gave my smile back to me :D