There is No Spoon

In the Wing Tsun system (and other chinese boxing systems), the "secret" behind hitting is to be completely relaxed. Mind you, we are not saying that you should be weak or limp, but to maximally release any tenseness from your limbs (and body for that matter). To develop this, the teacher repeatedly reminds the student to stay relaxed, to keep the fists open, to lower the shoulders, etc etc. As the student progresses, he learns to release all this tension from his body which, for the most part, results in a very weak punch, but then he gets to the next level where he gradually increases the power/force in his punch in which a heavy, yet relaxed, punch can be summoned at any time. Unfortunately, many wing chun/ving tsun/wing tsun students may not get to this level and confuse relaxed punching for powerful punching. (Which explains some of the horrible wing chun punching you see on YouTube).

To me, hitting in Wing Tsun is like "accidentally walking into a chair", while hitting in other arts (like karate, as an example) is like "to walk into a chair." The latter appreciates the presence of the object, while the former assumes the absence of the object. The idea of "absence of the object" is key to Wing Tsun hitting and incredibly difficult as our minds know what we see since we see what we see. To go beyond what your brain and eyes are telling you is incredibly difficult (especially under the stresses of a fight). As such, developing Wing Tsun hitting is not an easy task.

But have you ever accidentally walked through a chair? Notice how your leg just walks right through it, unknowingly, unphased and displaces the chair. Sure, it hurts RIGHT after, but for that moment - you hit it Wing Tsun style, baby! BUT, should I ask you to kick the chair, already your mind is inhibiting your body, subconsciously telling you that you HAVE to hit it, only to psych your body out resulting in you kicking at the chair. Kicking at the chair can do good damage by strengthening localized muscles in the leg used to kick it, but walking into the chair uses the entire body - and it is the sum of the entire body's muscles used in unison that is greater than what a kick could do. That is Wing Tsun hitting.

So you get the idea (hopefully) and as your training progresses, you can increase the UMPH! into your punch, while maintaining that same mentality of "walking into the chair" but with any and all of your attacks. Not easy but that's the idea and explains how a good hit doesn't require big biceps.