Though this is the place least expected to practice mindfulness I found it to be a real testing ground as to see how well one has mastered the skill of being mindful.
It is like taking the car to a highway after practicing on by-roads.
In a shopping mall you are bombarded with various stimuli in the form of sounds, visuals, and even fragrances, tastes through sampling even if you just walk through. Try to observe your reactions and intentions that crop up when you are confronted with various stimuli. When being aware you will begin to see patterns in your thinking. Objects or types of people you like more than the others and what you really don’t like. Later you can even review and ask yourself the question why you liked some objects more than the others. These are simple Practice to get to know yourself better.
When you have to walk long walks in a shopping mall why not try walking a distance mindfully being only with the walking. There is no need to really slow down.
Sit on a bench and try observe all the sounds that goes around without being involved. You will discover the usual silence in between the cacophony of the mall.