Shoulder mobility not your thing? If you suffer from pain or tightness in the shoulders try this exercise on for size! Wall slides are a great mobility assessment tool. You can start to see where range of motion starts to break down to improper form.
Even though this exercise seems simple, it is difficult! Be sure to pay attention to your back, wrists, and elbows. Making sure they remain in contact with the wall throughout the entire movement. If you can reach all the way overhead or reach the start position, move within the range you can, but push it slightly.  Expect fatigue to happen within 5-10 reps as you begin incorporating these in your routine.  If the wall proves to be just too hard at the moment, this same drill can be done on the floor as less intense introduction to the movement.