You don't even need tarot for such a case usually. Just promise yourself you are going to do what it decides and flip a coin. As soon as the coin falls and demands you to go particular way you will feel either joy or sorrow about the fact it has fallen this way and you are to obey. This will make it clear what do you actually want. Now you can forget about the promise and go the way you know you want now.

It also doesn't take to be particularly irrational magically-oriented mind to make use of some astrology, numerology, tarot or whatever of this kind occasionally - trying these and getting some shockingly precise data about yourself and predictions about events in your life is enough for a mind that is predominantly pragmatic although rational).