I think it comes from a generous impulse: after struggling with a problem for a long time, you’ve found something that works, and you want others to have what you have, even if you understand intellectually that it may not work for everyone, and that it may not even work for you, long-term.
Like a lot of people, I think, I constantly feel the desire to get life, the universe, and everything figured out and squared away, to finally dust my hands and say, “Okay! All set!” and just coast downhill through life from then on. Obviously, this is impossible; life is change, and nothing, not even good things, can be “all set” for very long. But a change for the better can feel permanent, because it initially seems so simple to maintain, and because we really want it to be permanent. And this is especially true of big, life-encompassing changes like diets, religion, and love. “Everything is good now, and all I needed was X!” So you want everyone to have or know about X, because it’s just so wonderful.
I think the polite thing for the enthusiast is to remember that 1) not everyone is in need of the same solutions, 2) the shine will probably wear off of this thing eventually, as it does for almost everything, and 3) even if this thing becomes a lifelong passion for you, and even if someone does genuinely need it, nothing works for everyone. Therefore, only offer advice if specifically asked, and even then, don’t say, “This will work for you!” but “Here’s what worked for me.”
For the person on the receiving end, 1) ignore when possible, 2) when it’s not possible, say, “I’m really happy for you,” and try to genuinely feel happy for them, remembering that they want you to share their happiness, which is a nice thing, and 3) wait for the shine to wear off.
