1. Play games! Here are a list of games:
Sudoku
Crossword puzzles
Solitaire
Cranium
Monopoly
Scene it
*When playing games, only play for roughly 15 minutes at a time. Any more could become tiresome and addictive.

2. Meditate. According to healthandyoga.com (physical benefits are nearly word-for-word), meditation has the following benefits:
Improves general health – meditating help blood flow, and thus increasing the amount of oxygen your cells receive.
Improves concentration – meditation conditions a person to focus on something. Thus, strengthening the mind.
Physical Benefits
Lowers oxygen consumption.
Decreases respiratory rate.
Increases blood flow and slows the heart rate.
Increases exercise tolerance in heart patients.
Leads to a deeper level of relaxation.
Good for people with high blood pressure (brings the B.P. to normal).
Reduces anxiety attacks by lowering the levels of blood lactate.
Decreases muscle tension (any pain due to tension) and headaches.
Builds self-confidence.
It increases serotonin production which influences mood and behavior.
Low levels of serotonin are associated with depression, obesity, insomnia and headaches.
Helps in chronic diseases like allergies, arthritis etc.
Reduces Pre-menstrual Syndrome.
Helps in post-operative healing.
Enhances the immune system.
Research has revealed that meditation increases activity of 'natural-killer cells', which kill bacteria and cancer cells.
Also reduces activity of viruses and emotional distress.

3. Learn something new every day! According to lifehack.org (modified slightly), some benefits of learning new things are:
Broader perspective in general
Increased skills in adaptation
Inspires creativity
Deepens character, thus one becomes inspiring to others
Increases confidence
Makes life worth living

Personal Story! As a dancer I have discovered that learning a large amount of routines in a short period of time has increased my ability to take on tasks, learn things quickly; understand my body, and handle stressful situations, including deadlines.