I spend a lot of time playing the numbers game and weighing probabilities of various outcomes as a running coach. Things come up for everyone, whether those things are the beginnings of an injury or just a scheduling conflict. A significant proportion of my job is taking a step back and making an intelligent decision about what approach gives my runner(s) the highest probability of success and, implicitly, the lowest probability of making the situation worse. Call me "Risk Manager in Chief" for Team Wicked Bonkproof.
The difficulty with all of this is the "taking a step back" part. This is easy for a coach to do for their runner, but really tricky for the runner because they are thinking of things from the perspective of "what training do I need to do in order to get better/faster/more prepared?" However, there are many times when doing less is a lot more productive than doing more.
My Own Example: Last week, I hardly went running at all. When I sketched out my plans for this Boston Marathon training cycle, last week was supposed to be somewhere around 110 miles, with about a marathon's worth throughout the week at or faster than marathon pace. Following a tune-up half marathon, which went according to my plan, I was set up really well for this approach. Then I got sick, and spent two days curled up on the couch with a fever, followed by a chest cold for a few more days. At week's end, I had run 15 miles. Inside, I was screaming, "I NEED TO GO RUN AND RUN FAST!" But, I kept myself grounded and waited, relying on the training that I have done to date to get me through.
When You Must Stay Patient: When you're working through some issue like being sick, or a persistent hurt spot, you need to ask yourself (and honestly answer), "Will running probably make this worse?" If the answer is yes, or if you are waffling, then you should just take a day off. Keep doing this until you get to the point where the answer to this question is a definite "No."
You're Not Losing Fitness, You're Just Not Adding Fitness: Again, the key to making this work is to focus on the training that you have already done. When you take some time off, even if it stretches to an entire week, you're not losing a significant amount of fitness...you're just not adding new. When you get back to work, you can add new fitness without causing any further problems for your overall training arc.
Just like a race mantra can be valuable, so can a rest mantra. To keep yourself patient, just keep reminding yourself, "Patience is rewarded, impatience is penalized." When you frame from that perspective, it makes it much easier to do the right thing.
And, for the record, I'm feeling better now and my goals for Boston are unchanged.