Call ins considered harmful

The play I made the session before last, which gave me my 18th best cash game no limit hold'em hand, was quite a risky one. I called a big bet from a player who had me covered, and had to go all in to do it. I hereby dub this play a "call in", short for calling all in. You need a stronger hand to call in than to go all in before anyone else has entered the pot. I learned why from one of Dan Harrington's poker books; here's the relevant passage:

The Gap Concept was first defined by David Sklansky in his excellent book, Tournament Poker For Advanced Players. If you're thinking of entering a pot that has already been opened, you need a stronger hand to call than you would need to open the pot yourself from that position.

Dan Harrington;Bill Robertie. Harrington on Hold 'em Expert Strategy for No Limit Tournaments, Vol. 1: Strategic Play (p. 188). Kindle Edition. 

Unfortunately, I don't have the Gap Concept completely ingrained in my thinking. Last night, I made two disastrous call ins. The first time, I was on an open-ended straight draw, and lost $11,054. The second time, I'd flopped a flush, but lost $35,399 when an opponent made a fatty on the turn. He raised to $30,000 on the river, and I called with my remaining $6,999. Part of me knew at the time of making each of these call ins that it was the wrong thing to do, but a bigger part of me was ignoring that knowledge. After my second reup, I was able to recover some of my losses.

During current Hold'em session you were dealt 133 hands and saw flop:
 - 11 out of 18 times while in big blind (61%)
 - 9 out of 19 times while in small blind (47%)
 - 50 out of 96 times in other positions (52%)
 - a total of 70 out of 133 (52%)
 Pots won at showdown - 13 of 19 (68%)
 Pots won without showdown - 6

delta: $-53,663
cash game no limit hold'em balance: $4,891,074
balance: $7,340,482