Quote Originally Posted by Biglines
Its not so much a case of thinking I have made X amount and then playing badly because of it - its more that you start feeling a bit too confident about your abilities over those of your opponents and so your play starts going downhill.

If we are talking about making +EV decisions and ending your session well, what should you be looking for as early warning signs that you might no longer be making +EV decisions and its time to take a break? (A list of things to look for would be very useful)
If you're playing good in terms of your ability and you're in a good mindset in terms of your ability, then no emotional responses can be +EV. The reason for this is simple: if you're playing and feeling your best, then you have no where to go but down during a single session. The idea is to take steps before your session to get in that best mindset (like I mentioned in OP) and to make sure you stay in that mindset until the very end of your session. If you start slipping, and can't get back to that mindset, then it's probably best to take a short break and relax and recover.