This list is modified only slightly from: Family fun brings enjoyment and health benefits. Please take a look at their site also, as it has some great ideas on it!
Start by taking an inventory of fun activities. Pay attention to what activities bring you pleasure. These might include tinkering in the garage, gardening, listening to music, watching UCONN women's basketball or reading. As long as the activity is consistent with your health, make time for more of it.
Link healthy habits to happiness. For example, stay motivated to do these exercises by choosing activities you enjoy. Vary your routine and exercise with other people. You might do some activities by yourself, and others may be group activities. Make exercise so enjoyable that the activity itself becomes its own reward.
Be attentive. When it comes to fun, quality counts as much as quantity. You don't always have to have more pleasure — just be attentive to it when it shows up. Instead of drinking a second cup of coffee, for instance, pay full attention to the first one. Sip it and savor it - don't gulp. After the first cup, you might feel complete with your coffee and reach for a glass of orange juice next.
Find fun. Try new activities. Explore new places and situations. Let your mind wander. Act impulsively once in awhile. Make a game of routine duties. And whatever the activity, try to find something pleasurable in the doing of it. Listen to the old adage - Seek and you shall find... fun!