parallel advice
There's a saying I often quote to my partner any time we're looking into getting some new tool, or equipment, or whatever:
Buy the cheap thing first; worry about buying the expensive thing after it breaks.
I probably heard it from Adam Savage, though I'm not sure if he made it up or if it was passed on to him from someone else. Either way, it's a piece of advice that's (probably) saved me multiple thousands of dollars over the years: I still have plenty of the cheap things that I bought, either because I haven't used them enough to wear them down or because they turned out to be resilient enough for my needs.
There's a saying that I work under a lot when I'm programming:
Implement it the quick and dirty way; if it's too slow, worry about optimizing it after.
I don't remember where I heard this one. But it's been a calming mantra to repeat to myself any time I work myself into a spiral over algorithms or runtime or memory usage... none of the potential optimizations that you could make would matter if it doesn't work. So get it working, and then you can worry about the details. Sometimes you don't even have to optimize it after the fact; It's always a pleasure to find that out.
There's a saying that I remind myself of every time I'm anxious about the future:
Worry about it later and you'll worry once; Worry about it now and you'll worry twice.
I can't control anything with regards to an upcoming appointment, outside of being prepared for it. If I am prepared for it, then there's nothing I could do in the present to affect it. So, it shouldn't be something that I should think about right now. I've settled more than a few anxiety attacks this way; logically working my brain towards calming down and shutting up about the things that it can't control.
If there's a common thread between the three previous thoughts, it's probably something along the lines of "deferring the stress for later." I'll work an expensive tool into the budget later, I'll write an elegant and efficient algorithm later, I'll deal with whatever anxiety-inducing task later... There's obviously a limit to how much you should defer, and sometimes there's no acceptable substitute for a large purchase or a chunk of good code or a few hours of prep.
But life is stressful enough as it is. I encourage you to step back once in a while, and ask yourself if it's okay to let the little things slip by for later. You might just find that you're more prepared to deal with it in the future, anyways.