Resigning from a game?

I wondered what peoples views are with regards to when and why you resign from a game.

I imagine it becomes more obvious the higher the level you play because the edges are so small but for me I can never really decide if i should resign or not. Should i play on if i am down a fair bir of material say two pieces and 2 pawns in middle/late game or should I always play the game out to checkmate? do you learn from playing handicapped in this way?

I know its not a very interesting subject but at times i think is it really worth playing this games out and wonder if its just me being lazy and wanting to move on to another game. What are your opinions on resigning?

Thanks :)

-FreeSolo

Yes i take things into account like king saftey, piece count of course, pawn structure and piece activity when deciding to resign.

I know it can be a little annoying when you are way up in all these parts of a game and yet a player still refuses to resign. 

I know when I am burried but sometimes when I am down a little i start looking for risky tactics/gambits since i am probably goinng to lose and can throw in everything with some form of counter attack and hope it works out. I know it is not sound chess but its better to blow up than fade away when you are behind looking at the board

Thanks for the advice Ashley :)

Resign when you feel it's hopeless. As simple as that.