Great Question! Agree with previous posters about showering at work, if you can.
Here's another option that's not 100% MMM since it's not 100% muscle power, but I thought it was a great compromise for me: An electric bike.
I live in the Washington DC area where, in the summer, it is hot and humid enough that you will sweat just stepping outdoors, doing absolutely nothing, let alone riding a bike or doing any kind of physical activity.
But, in the morning it's usually not TOO hot. With the electric bike, I can pedal just enough in the morning where I don't break into a sweat, using the motor to help take some of the work, and the breeze keeps me cool, even wearing work clothing. So, no changing or showering required when I get to work. I ride the 8 miles at a pretty leisurely pace, probably only about 14 mph, getting to work in about 30 - 35 minutes (can take anywhere from 25 - 45 minutes in a car, depending on traffic).
In the evening on my way home, I change into workout clothes and ride as hard as I can, not needing the electric motor (or using it only sparingly to get up steep hills, since the motor and battery are pretty heavy).
Some electric bikes don't allow you to supplement the motor with pedaling, or vice versa -- make sure you get one that does this, if you get one.
I got my bike for $300 at WalMart, far less than the cost of most non-electric bikes as I understand from serious bikers. The battery on this one is supposed to be able to go a maximum distance of 25 miles (about 40km???) before needing a recharge, which takes about 4 -6 hours maximum to fully recharge. You can take the battery out and just use it as a "normal" bike, too.
Like I said, it's not 100% muscle power, but let's be realistic. Most of us WILL sweat riding a bike any significant distance, and in certain climates you will sweat going 0 miles. And not everyone has a shower at work, or wants to shower at work, etc. So this way you can have the best of both worlds -- get some great exercise on the way home, while arriving to work already dressed, and not sweating. Good luck!