I've written a lot about motivation since I started this column, sharing what motivates me to train and be fit.
There's the motivation I get from wanting to set a good example for my kids. The motivation from feeling healthy and strong. The motivation I receive from fellow runners and the readers of this column.
All of that is positive reinforcement that helps me continue my fitness journey.
But not all motivation comes from something positive.
A few weeks back I received a rather well, let's just say not-so-positive email. It's the first critical email I've received since starting my Mission: Marathon (and now Mission: Fitness) column.
I was surprised and more than a little miffed. And it has me more motivated than ever before.
It's funny how strong you can become when someone criticizes your ability or expresses doubt in your strength and resolve.
The key is to channel the anger and frustration you feel when someone doubts you into a positive outlook.
It's the "I'll show you" attitude.
Yes, running with positive people who encourage you is incredibly motivating. That's definitely something I've discovered during my workouts with Team in Training.
But sometimes, when the training gets tough, I think about that email and anyone else who has ever doubted me. It helps me dig deep, find the strength to endure and keep going.
That strength paid big dividends a few Sundays ago when I hit a tough stretch during a hill training session in Knights Ferry.
It's critical for me to train on hills, because the San Luis Obispo marathon course features a lot of rolling hills. I need to adjust myself physically and mentally to running uphill and downhill, which requires not only different muscles, but a different mental approach.
One hill which goes by the moniker Big Bertha was especially tough. About halfway up I thought to myself, "You're not going to make it."
But that's when I thought about that email and I dug deep. I had something to prove to myself. So I kept going, attacked the second half of the hill and made it over in good standing.
Again, it's all part of the mind games you play to be an endurance athlete.
So if you've ever received criticism about your training in whatever sport I say revel in it. Use someone else's doubt to motivate you to strive further and get better.
You'll show them.
Reach Jim Silva at firstname.lastname@example.org. On Twitter: @mission26point2.