Unlike momentum as described by Newtonian mechanics, no external force is needed to stop human momentum. Today is day 6. I have already missed one day and could have easily skipped tonight.
Guilt is the primary reason I am writing now.
The training plan for my first marathon was 5 days a week for 20 weeks. I missed 2 days in total, one when my wife came to visit me in the US while I was waiting for my UK visa, one on the day I moved to the UK. Guilt pushed me to run on a few of those days, most days I ran because I wanted to run faster on race day. I trained even when it hurt, simply because that's what I thought I had to do. I was determined, but I was also inexperienced.
On race day, my IT band started to tingle at mile 9, and by mile 22 I had to stop for 5 minutes on the side of the road, crying, because I was in so much pain. I had just trained for 5 months and felt like a complete failure because I did not think I could finish the race. I kept going out of sheer
determination stupidity and hobbled across the line in 4:02, then collapsed. I was destroyed mentally and physically. Instead of being glad I had finished, I was disappointed with my time. I felt like I wasted 5 months because I had not finished in 3:45.
After the race finished and I could reflect, I realized how burnt out I had become. 5 days a week for 5 months. I overtrained and my body couldn't handle the stress. I stopped running for 6 months.
2 years later, I started training the Edinburgh marathon in May. I wanted to see if a slightly lighter schedule was easier on both mind and body and went with a 4 day a week for 16 weeks schedule. I even missed a few days throughout the schedule without feeling guilty. I knew I'd be alright as long as I ran the weekly long run. I finished in 3:59:31 and felt so good that I signed up for the Amsterdam marathon to take place in October of that year.
The entire summer should have been used for training, but it was particularly busy and I missed a good third of the training days. Worse still, none of my long runs had been greater than 15 miles the entire summer. I perceived myself to be in such bad shape that when we went to Amsterdam I thought I'd only be able to complete half the race. Charlotte and I made plans to meet at mile 16, and off I went. Unexpectedly, I felt great when Charlotte and I met each other. The training from earlier in the year prepared my body without overworking it, and the minimal training over the summer kept my joints and muscles distance ready. With no expectations of even finishing, I slowly jogged to the finish line in 4:12. I was elated. Even so, after 10 months of running (mostly) 4 days a week, I was tired and needed a break. I stopped running for the winter.
The following spring Zachary was born and for some boneheaded reason, I decided that I needed to start running again. Worse yet, I attempted to go from zero to hero thinking my body could handle anything after the 2 marathons the previous summer. I ramped up to a 15 mile long run within 2 weeks, and felt good.
The following week I tried for 17. While running up a lock on Regent's Canal in east London, I felt a sharp twinge in my right heal, not disabling like IT band pain, but sharp. I stopped, rotated my ankle a few times, and ran 7 more miles. Later that week I could hardly walk. Every step hurt. I tried running a few more times that spring, with the same result every time. My right leg hurt from under my heal to the beginning of the calf. Two and a half years and a round of physiotherapy later, I still haven't crossed the 10 mile threshold because my heal still hurts.
I can run 6-8 miles comfortably as long as I run slower than 8 min/mi. I'm too scared to run faster and I'm too scared to push past 10 miles because discomfort returns. I now realize that being unable to run is far worse than chosing to not run.
There's a lesson or three above that I would do well to transfer to other areas of my life.