Hand #1

He checked the turn/river. 4 to a row on the board, you can't beat the straight. Call me a chicken but I would have check / folded on this hand.

Hand #2

I believe the T was just enough to keep you in when you should have folded. The Q put another straight on the board. You have to recognize that you have the "dummie end" of the straight and play it like second best hand.

Hand #3
If you can't go all-in preflop with KK what are you waiting for? I would have had the same problem.

I've been guilty of all of the mistakes above and you'll learn from these.

Toughest part of playing holdem is laying down hands.