When you adopt a dog, there's a transition period in which you figure each other out. While it may seem like this takes just a few days, it can often take a couple of months. In that period of time, you'll learn what issues your dog struggles with, and what training you'll need together. And then comes the part where you're training your dog.
Of course, if you're a dog trainer, you'll snap your magic dog whispering fingers and the dog will be perfect after Day 1. But if you're like the rest of us mere mortals, it'll take a lifetime of work. Whether it's potty training or leash reactivity, door charging or crate training, you need to work at the training every. single. day. And boy, is that exhausting. Every dog struggles with something, and sometimes it seems like that one "something" is the worst thing in the world. We've had dogs surrendered to us for basic house training, for energy issues, for barking, for counter surfing, for crate training, and more. Your dog's worst habit may be something that another owner would love to have to deal with. But just remember -- your dog is not a "bad dog". Every dog has their own unique challenges, and loving them for their weaknesses and working on it with them is part of the job.
I'm not here to tell you how to train your dog (not right now, anyway). I'm just here to tell you - chin up! There are always going to be bad days. There are going to be setbacks. There will be days that make you scream and days that make you look at your dog and say, "Dude. We talked about this. No barking at the mailman, I wanted that Amazon package." There'll be days when you need a stiff drink or five, and days that you'll think, "I can't do this forever." Most likely, these awful days will come immediately after you've had a perfect day, and you'll get whiplash from your dog's about face.
In those moments, I want you to walk back in your house, put your dog in his crate, in his "spot", or next to you on the couch, and just sit. You don't need to beat this today. Let's try again tomorrow. And while you're both sitting and decompressing, repeat this promise to your dog like a mantra -- "I'll love you even on our worst days."