I find that just approaching the security area, I'll tense up having to deal with the BS and attitude of the TSOs. You never know whether they are in a yelling mood, what to handle your property, not give you access to your belongings per their own SOP, etc. Once through, I am immediately more relaxed and have less issues and very limited stress dealing with the airline employees or actual flight, even when irregular operations abound. Given TSAs BDO program, I would say this highlights how totally useless their program is as they have created the stressful situation, and the stress factors that someone may exhibit in the screening area are more a self-fulfilling prophecy than any valid indicator of a threat to aviation security. At what point do you experience the most stress when travelling?