A little more in depth to the previous reply:
In Sound Forge
For vocals, run a noise gate first. This will take some trial and error, so give yourself some time to figure out that effect. After that, you can either compress the track or you can use the normalize feature. Both do about the same thing by finding the peak value in a track and raising everyting up evenly near that peak, which raises the overall vocal.
Check your meters and make sure that the track does not red line or go over 0db. If it does, reduce the master corepsonding to the overun, i.e. if you are redlining at +1.2, reduce the master fader 1.2
Now you are ready to add the warmth you are looking for. After the previous procedure, you may find that the vocal is just fine the way it is. If you still want to add something, try adding some reverb. Be careful with the amount you add. The more reverb you add, the further back in the mix the vocal will "appear".