What's that about then? Every time I hear the phrase I find myself pondering the alternatives. If you aren't inevitably involved in lifelong learning you are going to proactively stop. How does that happen? Deciding that you have learned enough and preventing anything new getting in? Putting your fingers in your ears and singing "tralalala" whenever anything new comes near you?
I suppose it is analogous to the idea of retirement. "I've worked enough - I'll stop now" or "I've learned enough - I'll stop now". Neither of them appeal.