Breathing releases tension that can interfere with effective voice production. 

If you are holding onto tension, that tension radiates to the voice box muscles. 

Start by relaxing your shoulders and chest, then take a regular breath in and exhale. For the next breath, hold an "s" sound like in a hiss when you exhale. 

You want the focus of your breath to come from your abdomen and not your chest or shoulders. Place your hand on your abdomen as a reminder. 

Repeat a few times.

NOW S-T-R-E-E-E-E-E-T-C-H

A limber body means a more relaxed voice.

Start with side stretches, which are great for expanding your rib cage and making your lungs feel like they are full of air. 

Raise your arms up to the sky, exhale and lean to the right, lengthening your body. Gently hold it there for a few seconds, and then lean back to center and then to your left.

Gentle neck rolls will help warm up your neck and throat muscles.

Gently rotate your head clockwise and counter-clockwise.

Humming, lip trills and tongue trills are important, too.

A loose, gentle modulating hum will ease your facial muscles and create space for resonant sound. It gets your resonators warm, which helps restore your vocal tone quality.

Lip trills and flutters will loosen facial muscles and get your vocal cords warmed up, too. 

To roll your lips, close your mouth and create a constant "b" sound. This will vibrate your lips, creating a trilling sound effect.

Next, tongue trills relax the tongue and engage breathing and voice.

Place your tongue behind your upper teeth. Exhale and trill your tongue with an "r" sound. Hold the sound steady and keep the breath connected. Try to vary the pitch up and down the scale while trilling.

Articulation is one of the most important aspects of your job. If you don't articulate and enunciate clearly, listeners will not understand what you are saying, and you will not be hired for the job. 

Tongue twister exercises are a great tool for improving articulation. For instance ...

These are ideal phrases - and they are tough for me too!

Yawning naturally drops your jaw and regulates oxygen while extending your soft palate. It relaxes your throat muscles and vocal cords, and as soon as they relax, the tone drops. Many actors swear by this technique.

You could also do warm-ups in the shower! Humidity will help as the moisture will coat and protect your throat, vocal cords, and more. Acoustics in the shower are an added bonus. 

Wherever in the morning, in the shower or in your bedroom, kitchen or studio, warm-ups are important. Like an athlete, you need to warm up and train to keep your voice in top condition.