This is simplistic vague talk. "Being a wall," "lifting intensity" and "refusing to miss" aren't just mental buttons you push. You refuse to miss by hitting the ball a certain way (whether taking pace off or actually going for more), and that in itself is a conscious adjustment (and btw you're equating tennis IQ with tactical changes which isn't entirely accurate. Tactics are only a part of tennis IQ). Also, being a wall, isn't just running after the ball and keeping it in play. There's a lot of anticipation, strategy, positioning, etc...that goes into it, and again, these are adjustments the players make.