I think this is an unanswerable question, but a very common one. Defend oneself against what threat, exactly? People tend to think of self-defense skills kinda like having a fire extinguisher handy. If a fire happens, you grab the fire extinguisher and problem solved. Due to the wide range of threats one's safety, self-defense isn't so simple.
Even using the word 'tough' is precarious. I pose that 'smart' is far more likely to save one's butt from harm than 'tough'.