When you're using your stick for the first time it can be a little tricky to push up because the ingredients are a bit stuck to the tube. So the very first time you push it up it does require a bit more effort, but after that it will slide up and down in its tube easily.
Step 1 -Before applying too much force try holding it in your hands or place the whole stick under your armpit for a minute to warm the tube and soften the deodorant inside a bit :-)
Step 2 - Lay the closed tube on a flat surface press down firmly & roll it with the palm of your hand, this should loosen the stick from the tube. You can then steadily push from the base.
Step 3 - If your stick is particularly stubborn place your tube lid down and press your thumb down on one side of the base circle to get a little movement and then you should be able to push evenly from there :-)
1-2 Millimeters is all you really need to expose, If you accidentally push it up too far just firmly tap the base of the tube on a table (or ease it back down with the palm of your hand).