Exercise strengthens and builds muscles. Memory games will strengthen and build your brain the same way. With memory a use it or lose it' proposition, you'd do well to add memory games to your daily exercise program.
There are board games like Trivial Pursuit, Concentration, and Go to the Head of the Class that rely on memory. There are also simple games you can do alone to do the same thing. The easiest is to lay 10 unrelated things on a table. Look at them and study them for 30 seconds, then look away and try to remember them all. Now, as you look at them, say what they are and repeat it a few times. Then look away and see how many you recall.
One way to boost memory is to associate things with something more familiar, or to form a mental picture that will help you remember. If you want to remember that you left your book on the TV, picture a TV reading a book as you set the book down. Later, when you think of the book, you'll see that picture and will remember where you put it.
Songs and games that add things as they go along also build memory. "12 Days of Christmas" is an example of this. You say you can't remember 10 things, but you can remember all 12 things in the song. One reason is the mental picture of "9 ladies dancing" and another is the repetition. Say something repeatedly and it will be much easier to remember.
Many improvisational games build memory as well. In one such game, we had 50 people in a circle. We each introduced ourselves and did an action of a motion or sound that personified us individually, such as a huge guitar strum or a dance, and everyone repeated the name and the action. Each time a person said his or her name and did the action, that person did every preceding person's name and action, then did his or her own. The last person had to do all 50, and she succeeded in doing so.
I once had to memorize two 10-minute monologues in 3 weeks. I picked out key words and put motions to them, such as holding my hands up to indicate a picture, and squatting to convey sitting on a stool. The actions added muscle memory to my monologues and I memorized them so well, I can still do them with minimal preparation a year later.
Therefore, for exercising your memory the most important things you can do are:
1. Picture. Make a mental picture of the item in an absurd place or position.
2. Repetition. If you repeat something 21 times, you'll never forget it.
3. Action. Make a motion or sound that reminds you of what you want to remember.