Conviction

... is probably the opposite of second guessing oneself.

From personal experience, I can say if we'd like to e.g. hit that crazy high risk drop shot, then go for it all the way. Any second thoughts and we'll probably mess it up. Putting that doubt into the middle of stroke.

Even though I'm conscious of this self-sabotage, it still happens. Hopefully less so over time.

Same with anything we do on court really. Maybe not as critical for 1 out of 200 high topspin moonballs into the middle of court. But then again, for those shots, we're probably already pretty "convinced" of being able to make them.

I remember Davis Cup champ and captain Patrick Kühnen telling us during a clinic how crucial it is to be really clear what you want to do.

Seems straight forward - but to what percentage of our actions including the shots does that actually apply? In the middle of a rally, we e.g. tend to switch to "System 1" of more automated thinking and thus actions. There's not much time and many other variables kick in (this is where trained cue and habit kick in).

Put together, one should probably make a clear and concise resolution before a point, and then go for it. If things are going another way, adjust. Then review, improve, retry.

The trying part then, with conviction :)

P.S.: Another interesting aspect may be that even if we make an objectively "stupid" decision (shot selection, positioning), there's still a chance to win the point. Mostly, there's still how the opponent reacts. And again, conviction should increase the odds of staying in the point. vs drawing back because of embarrassment or even disgust. We can make the whole thing right next time. 

Play to win (esp on match point)

I see this quite often and have of course experienced myself: backing off on match point. 

That might still win the point and hence the match, but if it doesn't a few things tend to happen: 

Getting even tighter from then on. Handing over control to the opponent. And if the match does slip away, regrets: why didn't I go for it?

In a 2x2 of won / lost, and having taken  / given charge, it's probably always better to have taken charge. No or at least less "what if's". 

This might be another good tennis match - life analogy: if there's a seldom and important opportunity to grab something, go for it. We can still fail, but this way less to our own fault.

Of course other factors can be at play, like the overall strategy, what worked to get us to match point in the first place, the match-up with the opponent, our own abilities, etc. 

Either way, backing off compared even to previous points seems the wrong and less courageous way to go. (When on the other side of the net or down in a match, "backing off" might be strategy worth trying.)  

As a general guideline for matches though, I like the approach of taking fate into one's own hands, trying to decide what happens on court. So even when there's a loss on paper, we can count that part as a win for ourselves. Which may win us more matches down the road. 

Maybe in real life, as well :)