A hot girl in the office asks you for a favor, and you drop everything on your plate.
fuck deployment
fuck deadlines
fuck server isnt working
fuck my inbox is full

True Story
But I couldn't gather courage to ask her out :|

The only woman in our office is in her late 50's, needless to say im don't have your issue lol.

Same principle at uni. Hot girl in class needs help, drop everything. Anyone else... "Nah, I'm busy".

see by doing that you set yourself up to be used. if you can't fix the problem with a simple explanation then tell them you need to finish this part quickly and will be over when you are done. wait about 10-15 minutes whether or not you actually have something to do or not then help them.

@raves Has a very valid point, I used to help anyone, and all my 'family' and 'friends' encouraged me to run a business repairing PCs etc.

So few of them actually came to me once I had a price list and expected to actually be paid for my work.

"Can't you do mates rates?"

"How about supporting me financially after the years of freebies you got?"

"Uhm, it's ok, it's not that bad, I guess..."

Don't allow yourself to be used, bitterness isn't a great thing to carry.