I wrote this else where:
You know that phrase, your mind is your greatest weapon? It's very serious. YOU make the bag work and shadowboxing real. The ability to perceive an opponent, respond to attacks and bring intensity to bagwork IS IN YOUR MIND.
I see people all the time go through shadowboxing like it's a warmup. Or hit the bag in a 1-2-kick type fashion. thats DRILLING. Which is good. It's good to polish your technique specifically.
But there is a time when you need to shift your mindstate to the point of a moving meditation. Where you SEE an opponent. He IS attacking you... you ARE defending, countering, and intercepting.
That should be the state of your bagwork and your shadowboxing... A continuous flow of technique, motion, footwork, and ferocity should stem from you. An actual COGNITIVE RESPONSE to attacks that ARE coming at you.
IT IS NOT EASY and it can't be faked. Again, it will NOT come easy. You'll "know" what it is when you kind of zone out there. It took a LOT of shadowboxing to get to that point. I had to shadowbox till I got BORED (like 45min) before I really zoned out and started seeing things.
Make that shit ALIVE. It shouldn't just be some boring rote going through the motions thing. You should be able to teach yourself to flip that switch and get into combat mode.
Both. Polish your technique by drilling. Practice proper form, get it to be as internalized as sneezing.
Then turn it into something else entirely... add ferocity, add power, add explosiveness. Hit the bags with everything like you're really fighting. Make the techniques flow from you.
If you drilled jab, lead upper cut, low right kick, you should have that combination "inside of you" but not just throw that... you should be able to throw that combo, check a kick, quick switch, throw a left kick, straight right, left hook, right kick, teep... and just flow.
when you hit pads, your coach will eventually move you up to 'see & hit' where it's not just drills you're going through. but you'll know what signals the pads at certain angles are and he'll just hold stuff up... if you aren't fast enough you missed it...
you just hit what you see... you have to be in PERFECT stance and position all the time or you'll miss it...and with a good coach/padholder you'll flow through techniques seamlessly...
which prepares you for when someone is firing back at you and there are little openings and gaps in their technique for you to take advantage of and when you SEE it you have the reaction time required to HIT it.