How can I make a long voice over track all be around the same volume?

[Trebor]

… have it actually modify the amplitude of the sound to sorta “even it out” so it is all around the same volume level… so make loud parts quieter and quiet parts lounder…

Anyway… is there anything like this? Or a method you now to do this?

Dynamic range compression … Compressor - Audacity Manual

LevelSpeech2 is a compressor-limiter combo plugin for Audcaity.