Will does not mind his daily fifteen minutes of tummy time.
His mother, on the other hand, sometimes has to try not to mind when Will spits up all over her bed/sofa/favorite blanket from Restoration Hardware.
It's all about timing. If he's just eaten (which is pretty much all the time, except when he's sleeping and thus exempt from TT), Will is sure to mark his territory with a bit of regurgitated formula wherever you put him.
And if he hasn't just eaten? He'll go easy on you by sticking to good old non-staining drool: