David Goggins, a retired Navy SEAL and endurance athlete, believes that the true purpose in life is to better oneself and push past perceived limits. He emphasizes that individuals are their own purpose, rather than searching for external meaning. Goggins encourages embracing discomfort and pushing through challenging situations, even when the mind suggests it's impossible, as he advocates for the "40% Rule" where we are only at 40% of our potential when we think we're done. He also stresses the importance of taking responsibility for one's life and not making excuses.