How do you handle bad and good runs?

When im on a bad run i get this really sick feeling in my stomach and i imagine taking my remaining bankroll and doing something stupid with it to make up for the losses. (Like signing up for the Sunday Millions or sitting down at a $2/$4 table). I've done something like that a couple of times and more often than not it worked. But every now and then i lose about 90% of my Bank Roll and spend the next 2months rebuilding it playing $2 HUs and $1 Singles.

When im on a good run, i get to cocky and start playing like crap.

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G.T.S