If you look around the blogosphere these days, you'll see that there are plenty of people out there on the D.L. Heck, I'm trying to stay off of it myself right now. One thing that can help all of us is to step back and rest when we need it.
I know it's a hard thing to do; no one wants to miss training. But sometimes, when we're run down, or when we're aching, it's the right thing to do. A couple of days off in these cases is usually worth it's weight in gold.
Rest is important even when you're not feeling tired or sore, too. Unless you're an elite, you need to schedule in at least one rest day per week. When you work your body hard, that's great. But if you want all the benefits of that hard work, let it rest for a day and catch up. Skipping rest can lead to a downward spiral of overtraining, injury and burnout. Don't go down that road.
I'll leave you with one final thought--a couple of times in the past when I've been injured, I could look back at when that injury first started bothering me. I said to myself, "I wish I'd just taken a couple of days off." Had I done just that, what turned out to be long-term injuries might have only amounted to a few days off. Learn from my mistakes!