I'm kind of doing this in backwards order, since I haven't really explained the three guna yet, but I want to share a "Mental Constitution Chart" written by Dr David Frawley (slightly shortened from his book Ayurveda and the Mind). I really like this chart because it doesn't just lock you into a box, it invites you to make changes in you life. It also gives a good idea of what each guna involves, so I guess, in a way, I am explaining them!
DIET a) Vegetarian b) Some meat c)Lots of meat DRUGS, ALCOHOL a) Never b) Occasionally c) Frequently NEED FOR SLEEP a) Low b) Moderate c) High SEXUAL ACTIVITY a) Low b) Moderate c) High SPEECH a) Calm and peaceful b) Agitated c) Dull CLEANLINESS a) High b) Moderate c) Low WORK a) Selfless b) Personal goals c) Lazy ANGER a) Rarely b) Sometimes c) Frequently FEAR a) Rarely b) Sometimes c) Frequently DESIRE a) Little b) Some c) A lot PRIDE a) Modest b) Some ego c) Vain DEPRESSIONa) Never b) Sometimes c) Frequently LOVE a) Universal b) Personal c) Lacking VIOLENCE a) Never b) Sometimes c) Frequently CONTENTMENT a) Always b) Sometimes c) Never FORGIVENESS a) Easily b) With effort c) Holds grudges CONCENTRATION a) Good b) Moderate c) Poor MEMORY a) Good b) Moderate c) Poor WILL POWER a) Strong b) Variable c) Weak CREATIVITY a) High b) Moderate c) Low SPIRITUAL STUDY a) Daily b) Occasionally c) Never MANTRA. PRAYER a) Daily b) Occasionally c) Never MEDITATION a) Daily b) Occasionally c) Never SERVICE a) Daily b) Occasionally c) Never
No cheating, only enlightened beings are pure sattva, the rest of us will have to settle for Rajas moving towards Sattva, which is far preferable to tamas. If you want to build sattva, look at the a) list and see what can be improved in your day to day life. At it's essence Sattva is a peaceful mind, so don't develop rajas in the mind in you ambition to be a clean freak or super creative. Just do works for you.