If you break even you're still playing better than the majority of your opposition. At least you're beating the rake.

Cheer up, think once more about why this specific game should be +EV for you, chase your edges and stop chasing where you don't have edges. Don't bluff calling stations or make hero calls etc.

If at any point during a session or on a table you cannot clearly see how the money is going to flow from the players at your table(s) to you - stop. If you can look at one guy and you know you can exploit him by not bluffing and value betting your solid hands you are in a good game. If you can see another guy and know you can play trash against him and get him to fold because he gives way too much credit you're in a good game.

Your measure of whether to continue a session should never reflect recent or distant results. The recent history at the table is a WEAPON you can use. Ok, so maybe they lucked out, but would your play seem solid or bad to them? How does that effect your image? How can you EXPLOIT that? How can you exploit every player at your table and make the money flow to you.

EVERY time you make a correct pre-flop fold a little more EV (EVs are baby monies, remember) flow to you.

Don't get fancy, don't get frustrated just play solid, play in position, play aggressive and above all - exploit your opponents.