I snipped out a couple quiet parts, spliced them together, and normalized to bring up the levels. It does sound like something with a motor in the background, possibly an A/C unit as suggested. Maybe a faint dog bark as well (?)
My own mics will pick up a quartz clock ticking about 6 feet away that I can't normally hear.
I wouldn't use any treatment on your track. At home, I use EQ with a high pass filter to remove most lower frequencies. In my office at work, I have an extremely loud AC vent above my desk that makes recording very difficult. There, I have to use a dynamic mic (Heil PR40), and then remove most of the background noise with SoundSoap 5+. Audacity has a noise reduction feature that could completely eliminate whatever little noise is in your background, but I'm not sure if it would be necessary. Using EQ in Audacity to remove the low (lower than a human voice can create) frequencies without affecting the sound of your voice.