Be sure, before you get to the gym, you don’t let yourself get mentally involved in anything that can destroy your concentration.
If you have a hobby or something other than your training, keep it out of your mind the hour before going to the gym or you’ll end up at the gym “flat” without the proper motivation or the drive you need to work hard. The best way to arrive at the gym in the right frame of mind is to spend some time before you get there thinking about your workout.
Visualize the exercises you are going to be doing. The amount of weight you will be using. The actual form on each exercise. Especially those that are more difficult. And especially those exercises where the perfect form cam make an exercise a monster for growth.
Like the straight bar on the Scott Preacher bench for lower biceps for instance. Or it may be supine dumbbell extensions on the flat bench for lower triceps. Donkey calf raises for stunning calves.
These and others exercises like them require some mental preparation in order to tease extra growth where no one else has it.