Because it worked for me. Strength training helped me overcome the RSI and back pain which plagued me while I was still inclined to overvalue the intellectual over the physical.

Given NFL players tend to be carefully trained and I would assume as strong as possible, why do they tend to have shorter than expected life expectancy? Or world class athletes in general? Doesn't that show that going to an extreme and being as strong as possible perhaps isn't actually leading to a longer life?