I agree with rubthebuddha and the others in regards to the tension/relaxation exercises… If you have a problem with tension you first need to be aware of what tension is before your body can understand relaxation.
Pay attention to your breathing… most people stop breathing normally when tense. Focus on your exhalation.
Are there specific areas during your workout where you feel more tense than others? For instance, are you more tense during forms (if you do forms) or during sparring? Or perhaps both?
If you are tense doing forms, perhaps it’s because of your mental imagery? Some people think “I need to show a lot of power” or what not when doing forms and it gets translated to your body as “be TENSE”. So, by changing your mental image from “power” to “speed” or “fluid” may help you a lot in overcoming tension in this area.
If for instance you are having problems with tension during sparring you could use a partner exercise such as “slow-sparring”. Start working at a real slow speed (read: slow-motion) and concentrate on keeping your body relaxed, biomechanically correct/efficient and last but not least BREATH! Be fluid in your movements and stay consistant with the speed of your movements. Move your body just enough to get away from your partner’s strikes. Roll them off, slip, parry or whatever, but don’t use jerky movements. And don’t think too much about how to block, just keep in constant motion (don’t stall), evade and strike back when you see a opening. Again, GO SLOW and remember to BREATH!
BTW, moving slowly doesn’t mean you can change the physics of a strike. Once the strike is deployed make sure it stays in that force vector, i.e. don’t track your opponent. For instance, if you throw a right straight punch and you see your opponent move to your left, don’t all of a sudden change trajectory… finish your movement. You get the idea.
The idea of this drill is to get you relaxed and reduce your fear-reactivity (cause I bet that’s part of your tension problem). You’d be amazed at how difficult this is at first. BTW, these principles can also be used when grappling.
There are other drills which help different areas of relaxation, but I won’t bore everybody here. The above are just a couple of ideas I currently use in my own training and also when I teach others.
KG