Life isn't fair. It's true, and you still have to deal with it. Whining about it rarely levels the playing field, but learning to rise above it is the ultimate reward.
Just because an employee does things differently doesn't mean he or she won't do the job right or as well. If you establish expectations of the goal and the standards to follow, then methodology shouldn't be an issue.
The annals of business are filled with stories of companies that thought they had it made and could milk their enterprises without having to bother about improving their products or services. It's amazing how fast they found their markets disappearing.
You don't need a big close, as many sales reps believe. You risk losing your customer when you save all the good stuff for the end. Keep the customer actively involved throughout your presentation, and watch your results improve.
If you find yourself plagued by a recurrent worry, train yourself to think of something else. Your conscious mind can concentrate on only one thought at a time, and driving the negativity away will free you up to move forward again.