You know that feeling when you're lying in bed at night and the fridge suddenly goes quiet, and you realise how loud it had been?
You may not have been conscious of it bothering you. It may not have been bothering you at all. But still you think "Oh, this is nice. What a relief."
That's what it's like for some people (there are no rules) when they realise they're trans, and do something about it.
Only it includes everything in life, not just the fridge.