เหนื่อยจัง

No, it's not rude, but it is informal. It's perfectly fine with friends, family, and colleagues you are close to.

Yes, absolutely. Both men and women use it. Men might follow it with 'ครับ' (krap) to be polite but still informal.

'Chang' is more emotive and subjective (like 'so tired!'), while 'mak' is more factual (like 'very tired').

Yes, it's very common for mental exhaustion. For deep emotional pain, 'เหนื่อยใจ' (nueai chai) is even better.

You say 'ไม่เหนื่อย' (mai nueai). You don't use 'chang' in negative sentences.

Yes, 'เหนื่อยโฮก' (nueai hok) is very popular among teenagers and on social media.

It's a way of venting or acknowledging one's own effort. It's very common in Thai culture to speak small feelings aloud.

Yes, it's an intensifier used with adjectives, like 'ดีจัง' (so good) or 'สวยจัง' (so beautiful).

Definitely not. It sounds too casual and like you are complaining about work before you even start.

Say 'สู้ๆ นะ' (Su-su na) which means 'Keep going!' or 'You can do it!'.