Re: The mental game
You absolutely need to visualize while training. I have no idea how a person can handle boxing training without visualizing. I would have quit a month into it because it would've been so boring.
And from your post do you mean you're a beginner (only sparred a handful of times)? If so you don't need to worry abut the mental game. As the last post said, work on muscle memory first.
When you're a beginner you will suck at boxing. Emotionally, this is difficult because you know you look like an idiot ad it's embarrassing/frustrating. You just have to say oh fucking well, it is what it is. When you spar, you'll have emotions like anger, frustration, embarrassment, fear, etc. That's because it's new to you. Just remind yourself it's only a fight....it's only a fight. As you spar more you won't have those emotions and it'll become like a game to you. You'll be able to intentionally do stuff that makes the other guy have those feelings. You'll be able to switch off your emotions and turn them on or fake them when you need them (maybe not...I'm kind of a sociopath). For example, when you take a big shot in sparring come back with a really hard combo (think Erik Morales). You look like you're doing this because you're angry about getting caught, but in reality you're only doing it to get the guy off you so you can recover...if he thinks he pissed you off he might take a step back and assess the situation rather than following up on you. That might be the split second you need to get your head back.
So if you're a beginner, for now focus on muscle memory and visualization. And in the ring, don't get caught up in it....don't put the pugilism on a pedestal. it's just a fight. Tell yourself that as often as you have to until fighting is just normal to you.