I believe our mind (esp. our memory) is like a muscle. If we don't
seriously use it, it tends to age, weaken and lose capacity.
Over the last 5 years, i spent 2009-2011 in the US on my own —
tremendous learning and improvement, perhaps the most active learning
period in my professional life. Then after I came back to SG, i
studied financial math program, c#/dotnet, and some c++.
I feel the serious study keeps my mind active. However, over the last
18 months, I notice various signs of my learning capacity reducing,
but it's not all due to aging —
* biggest factor is lack of concentration, due to kids and family commitment
* not enough time to periodically re-visit each topic,
After all, I feel it's vital and paramount to keep our mind in
constant learning mode. 活到老学到老.