Below is a shoulder strengthening routine that I have found to be effective for a quick workout during lunch (50 minutes). It consists of 3 sets of 12 at a comfortable weight (80% of your max.). Try it out for a few weeks and let me know what you think.

1 Mile Run – Warm up
Standing Military Press
Barbell Up Right Row
Barbell Shrug
Barbell Front Raise
Dumbbell Lateral Raise
Dumbbell Arnold Press
60 sit ups
Stretching