Whether you skip caffeine to get better sleep or have trouble waking up either way, this quick breathing exercise boosts your energy and helps your brain wake up. Try it in the morning, or even in the mid-afternoon when you're starting to drag a bit.
If you're doing this in the office to beat the mid-afternoon energy lull, find a quiet spot like a stairwell or unused corner. Rest your arms gently at your sides, stand up straight and close your eyes. Inhale deeply through your nose and raise your arms above your head. Take as deep breathes as you can, try to feel your rib cage expanding. Exhale fully and lower your arms. Repeat for 30 seconds. As the video above shows, you can do this exercise for longer, but 30 seconds will give you the right effect if you don't have much time or privacy.