I'm in my late twenties and yet I still go through phases. Writing is a constant, but (as examples), I've recently been obsessed with a) playing an online game to the point of addiction, b) spending too much money on (cheap) shoes, c) Buying BPAL perfume (still ongoing) d) watching Panda Cams.

My phases tend to start slow, then become very obsessive, until I realise I'm wasting time/money. This is why I don't gamble or do drugs - I don't think I could do either 'safely'.