David Goggins methods might sound inspirational, but his constant inconsistency in how well he's doing are a symptom of PTSD. I went through similar experiences. Extreme physical exercise is effective at dealing with flashbacks, fight flight freeze, panic attacks, anger, anxiety, etc in the moment. Extremely danger activities also help you feel like you're okay since your physiological responses match your environment and the activity is a distraction that takes up all of your focus. For example jumping off cliffs is calming. It's hard to stop doing physical activities at the same time you're dealing with flashbacks and having panic attacks, and it can be an escape. I've ended up biking, running, and swimming for 6+ hours because of it.
It is painful and is debilitating to live normally. Treating your PTSD is better so you can be consistent and just be okay by yourself without a distraction. PTSD cam also get worse over time for some people. The brain is kinda garbage at dealing with mental stressors and using physical stressors is effective at dealing with symptoms in a given moment. However, avoiding reprocessing the thoughts and beating yourself up doesn't help you move forward. It's also a dangerous process to do without someone experienced.