Actually, regarding positive mental attitude, a short tale of someone here who caved in to negativity.
A friend I knew here recently came back from her trip home (England) at Christmas and was just wallowing in misery. She'd been here less than a year. On her return to HK in January she was jetlagged, missing her friends & family and would sit posting on Facebook in the early hours of the morning how unhappy she was and moaning about HK.
What didn't help were the friends back in England who pretty much begged her to come back. She ignored invitations from her friends here who really tried to get her out and cheer her up. Anyway, claiming her husband's company wanted him back in the UK, they had moved back to the UK by Easter, I didn't even get a goodbye from her.
It was a real shame, if she had just let herself get out of that mindset I am convinced she'd be having a ball. (convinced because I'm sure a lot of us have moments where we'd just jack it all in and go, but we get past it)