Yep, it's all about training. How many strikes have I blocked that were 100%? Actually, in our dojo, we have a little contest when we do step sparring (like 1-step or 3-step). The striker's stated goal is to try to tap the blocker (not hit them hard, but throw the strike as FAST as you can, just very little power. In other words, stay loose and don't put the kime at the end). This way each of you has a goal and an opportunity to "win". Try this: if you have a heavy bag or something, throw a punch at it with the most speed you possibly can, but no power. Just stay relaxed through the entire strike. You'll see that you have the same speed as a normal attack, and when you make contact with the bag, it won't move. If you do that against an opponent when sparring, the most they feel is a light slap if you catch them. That's how we train.