The technical aspect obviously requires proper practice for you to hone your skills. Here are some things that have helped me on the mental side.
1. Attack the ball rather than react to it. When you commit to coming in for the volley, assume the ball is going to be hit within your reach. Don't waste a millisecond to process the decision of "If it's close enough, then I will hit it. If it's not within reach, then I will not hit it." If the opponent hits a near-perfect pass where only an instant reaction on your part will save the point, taking the time to make the decision of whether or not it's within reach can be the difference to whether you actually could have gotten it or not. This leads me to my next tip.
2. Don't be afraid of making a spectacular lunge for a volley... and end up swatting empty air. When you come up to net, sometimes you will get passed. Take it as a fact and get over it. There's no shame in getting passed. Don't worry about "If I had stayed back, I could have returned that last shot." Coming up to net is a gamble which increases the odds that the point will end on the next shot. Once again, perfectly segueing to my next tip.
3. Choose when to come in to volley wisely (in match time at least). Since coming in escalates the odds, you want to make sure you do it when they're in your favor. If you really have no feel or sense for approaching, just approach all of the time when you're practicing with a buddy. You'll get a feel for which of your opponents shots you can hit better approach shots off of, as well as what parts of the court you hit better approach shots from.
4. Approach shots are very important. No matter how good of a volleyer you are, if you come in to the net after hitting the opponent an easy sitter, you can expect to: a) get passed; b) get lobbed; c) get a fuzzy ball slammed down your throat. If you notice yourself consistenly having to go to rediculous lengths just to hit your volleys, you might want to consider if your approach shots are what you need to fix first. If you come in behind a good approach shot, you should be the one feeling in control of the point. Of course, even if you do hit a great approach shot and expect little more than a weak chipped floater back your way, don't get complacent and sloppy. Recall tip 1 and attack the ball and don't let up until you've taken the point.
5. Don't be afraid of getting hit by the ball. Assuming the opponent hits the ball from the baseline or further back, even if he nails it, unless it hits you in the face, it shouldn't be a big deal (unless you're 80 and you play guys 50 years younger than you
). By the way, the odds of the ball hitting your crotch are too small to even consider. Aside from making you seem like a wuss, the problem with worring about getting hit is that if you're brain is trying to simultaneuosly process how to both hit a good volley as well as protect your body from what you mistakenly interpret to be an utlimate and untimely death, your brain's naturally going to give more focus to the "survival" response. Rather than thinking "I will asses the opponent's return and use the information to determine if it poses a threat to my livelyhood. If not, will hit a good volley
," think "I will asses the opponent's return and use the information to return a good volley
." It's kinda like tip 1.
There's my 2 cents.... and some change.