Surround yourself with uplifting people, positivity can be contagious seek out those who radiate optimism and support limit time with chronic complainers.
You don't want to be viewed as the complainer, and so you except, and maybe either are complicit with sweeping a lot of things under the rug because you just want to do your work.
Whether you call it decline or not, the moaners are on to something: America has indeed produced many of the innovations that have made their way into global (and British) English, for better or worse.