Reddit reviews How Bad Do You Want It?: Mastering the Psychology of Mind over Muscle

You've got a ton of responses, but since this was a long long long time goal of mine I'll chime in. First off I ran 3 years in high school and my PR was 20:04. When I started running again at 33 in 2014 I decided my primary goals were a 4 hour marathon and to be faster than I was in high school (sub 20 5k). I achieved sub 20 in August 2017. Really the "secrets" are not secret and the training is the same for everyone.

1. Deal with injuries proactively!! I have lost so much time to injuries it's downright silly. I've also spent so much time training through things where I just didn't get faster. I'm a little torn, in some cases I think I was hurting myself, in others I think I did the right thing. Learning the difference between an injury and a niggle is huge.
   
2. Weight. I Hate to say it but being a healthy weight is critical. 20 minutes unless you have some really good genetics is just fast and carrying extra pounds makes that much harder than it needs to be. I'm 5'10" and 160 when I broke 20 (and I could lose more) but I was ~195 when I started.
   
3. Train consistently. Running 5+ days/week for months and months and month will yield improvements. They may not come as quickly as you would like, but you will improve!
   
4. Run more. More miles always helps. I used to tell people I'm the slowest person I know who runs 30 miles / week. Then I was the slowest person I know who runs 40 miles per week. I think I was averaging 45 with many 50+ weeks under my belt when I finally broke 20.
   
5. Strides, strides, strides! Do strides 2-3 times per week. Some speed work is critical but just practicing running fast while staying loose is really important. Eventually I just felt like my hips learned how to achieve a nice high cadence without it being a strain and I credit that mostly to strides.
   
6. Train where you are, not where you want to be! Unless you're really close (say sub 20:30) going out and running 400s at 6:26/mile isn't the training you need. Find a plan that you trust (JD, Pfitz, Fitzgerald, Hudson, Tinman, etc) and follow it. I personally love Pete Magill's free plan on RW. By the same token, don't sweat the paces on your workouts too much, you will taper for your race and lots of things happen during training including fatigue, lack of sleep, heat, humidity etc. I think most of my 5 minute fartleks came in at ~6:40-50 in the month before I broke 20 (it was hot and humid the whole month, race day was cool and crisp). That said I did hit the track once for 16x200 and I was running comfortable 42s where in the past I had always struggled with anything <= 45.
   
7. Work on your mental game! Insert shameless plug for How Bad Do You Want It!! I was hurting at the 2 mile point, my hamstring was doing something funny which altered my stride and I my mind was saying "there are 5ks every weekend, back off and try again next week" and I know that in other races I've backed down at that point but I started mentally chanting "No Regrets" to myself and I shut down the bad zebano and ran a 6:17 final mile. Find a way to fake the confidence if you don't have it, find a way to keep running hard when you want to quit.
   
   Best of luck to you