How can I keep my brain cells longer?

I don't want them to die out quickly. What can I do to keep them longer? Eat fish?How can I keep my brain cells longer?
The best way is not to smoke, drink or take illegal drugs all of which will destroy brain cells. Now to help develop more, exercise you brain by working puzzles like circle a word, crossword etc. Read a lot of books that make you think. Doing mathematical problem solving also helps to exercise your brain. Eat a healthy diet of fruits, whole grains, greens and veggies. Cut back on soda, junk foods, sugar and fats.
Simple answer to your question: Keep using them!
Do crosswords, Su-Dokus, memory training exercises. There are so many things. The more you do, the lesser the rate of decay!
You could try using less of them and not asking stupid questions i've also heard that doing drugs is bad for brain cells. Don't drink, head bang, use drugs, participate in violent sports.. those sorts of things.. fish, along with a healthy diet will help. Good luck.