Ask HN: How do I improve my memory?

I feel like my lack of discipline over the years has gotten me to a point where both my short term memory and my long term memory have suffered greatly. I have trouble focusing and holding pieces of non trivial systems in my head. Sometimes, at the end of the day, I barely remember any of the interesting things I've read during the day. A day after watching a technical presentation, I barely remember the main points it addressed.

I'm not looking for quick solutions, but rather what exercises or life style changes should I adopt to improve my memory?