Why run outside?

I write about what to wear running and mostly focus on outdoor gear because, in many ways, running outside is better for you than doing all of your runs on a treadmill. Why run outside instead of on a treadmill?
1: Avoid RSI - a treadmills constant flat surface puts you at risk for a repetitive stress injury. Yes, part of what makes running outside hard is that you're constantly working to avoid uneven pavement. But that dodging and darting prevents overuse of muscles and builds up ones that don't get used on a treadmill.
2: More race-like - races are run outside (can you imagine a race where everyone ran on treadmills next to each other? Where would the cheering crowd stand? How lonely would it get as people finished there 10k and then just walked off, leaving empty treadmills behind?!). Get a feel for outdoor terrain by doing some of your training runs outdoors.
3: Be Mr. Rogers - if you're as old as I, you remember Mr. Rogers singing "These are the people in your neighborhood." It's easy to avoid the people in your hood if you spend all your time at work, the gym, or inside watching TV. A morning run on the weekend is a great way to get to know your neighbors. The key: Say hi to everyone you pass.
4: Pride - on a frigid Monday morning, coworkers' jaws will drop when you tell them you ran outside over the weekend. And even if you don't tell another person, when you're out there in the wind, rain, snow or sweltering heat, you'll feel invincible (Assuming you're dressed appropriately).
5: Reclaim your youth - when we were kids, we didn't play on treadmills. Running and biking outside are the two things I do regularly that make me feel like a kid again. It's the best!

Running tip: 3 things can make running outside suck.
1: Under or overdressed. Too hot or too cold can ruin a run. Check the temp, look out the window and, when in doubt, layer.

2: Getting hit. Running at night or dusk/dawn? Dress to be seen. A safety vest or flashing headlamp might not seem cool but you know what's really uncool? Being hit by a car or bike!
3: Bad terrain. Yes, avoiding potholes will help prevent RSI, but accidentally stepping in one at the wrong angle can cause a sprain or break. Enjoy the fresh air but keep one eye on the ground.

Happy running!