BE58 PLT DEPARTS WRONG RWY AT ATL.

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THE DEP ATIS WAS CALLING FOR DEPS ON RWY 8L. I WAS CLRED TO TAXI AND HOLD SHORT OF RWY 8L AT INTXN D FOR INTXN DEP BEHIND COMPANY LEARJET TFC. TWR CLRED ME FOR TKOF AND I PROCEEDED TO TURN ONTO THE RWY AND STARTED TKOF ROLL. AT APPROX 500 FT AGL; TWR INFORMED ME I HAD DEPARTED RWY 26R AND TO TURN R TO 360 DEGS THEN ON COURSE. NO TFC CONFLICTS OCCURRED AND THERE WAS NO SHORTAGE OF RWY AS TXWY D IS AT THE MID POINT OF A 10000 FT RWY. FROM THE BEGINNING OF THE TAXI FOR TKOF; I WAS RUSHING FOR DEP AND PREOCCUPIED WITH MY DEP PREPARATIONS. I WAS LATE AND THE WX WAS MODERATELY LOW -- ALL FACTORS THAT INCREASED MY ANXIETY AND HASTE TO DEPART. I AM VERY FAMILIAR WITH THE ARPT AND I BELIEVE THIS ALLOWED COMPLACENCY TO SET IN. THE DEP FROM MIDFIELD MADE IT DIFFICULT FOR THE ATC CTLR TO ANTICIPATE MY MISTAKE. A GOOD LESSON. COMPLACENCY IS THE MAIN PROB HERE. EVEN DOING THE SAME THING EVERY NIGHT (SAME RUN; SAME ARPTS; ETC) DOES NOT ALLOW A PLT TO BECOME TOO COMFORTABLE; OR COMPLACENT. I WILL NOW BE VERY SUSPICIOUS OF COMPLACENCY. ALLOWING ONESELF TO BE RUSHED INCREASES CHANCES FOR MISTAKES TO HAPPEN AND GO UNNOTICED. SLOW DOWN; THINK! BE SUSPICIOUS AND THINK THROUGH INTXN DEPS. CHK HDG INDICATOR ON LINE-UP TO VERIFY DEP RWY. SLOW DOWN TO ALLOW CTLR TO STAY IN THE LOOP AND HELP TO AVOID MISTAKES.