Before recording audio you should always check your levels. In Windows this is done by right clicking the speaker icon in the lower right near the clock and selecting "Recording Devices" this opens a new window and notice next to the device you're using to record there is a stack of a few bars and when you make noise they'll light up green. If the green is constantly hitting the top then your levels are set way too high thus creating the audio clipping(this crushes a huge range of frequency). This can be fixed by clicking on that device then clicking "Properties". This will open a new window then click on the "Levels" tab. Lower your levels a bit and speak into the mic to see if the green bar is still hitting high. Keep adjusting this until your levels aren't clipping. It's also helpful to have recording software, such as audacity, open as well so you can actually hear what these adjustments are doing and they'll usually have a more accurate level meter.
Another advantage of having better levels is that you can speak with a more animated or lively voice because the device will be able to capture a larger range of frequency in your voice without clipping. The advantage to sounding more enthusiastic or lively is that it'll carry that energy in your voice to the person listening and they'll be more likely to keep listening. Often times when recording my voice I realize I lose the energy really quickly and have to keep doing take after take. What kind of helps is just trying to keep a smile on your face and, well at least for me, it'll make my voice seem a bit more energetic. Though this has always been a problem for myself since I tend to speak monotone naturally.
