Psychic force can be regarded as a more focused, more powerful form of psychic energy. If psychic energy is like the flow of a river, psychic force is like a lightning bolt through your brain.
Gaining a psychic power is relatively easy; the hard part is having enough internal clarity so that the associated psychic force doesn't destroy everything in its path.
Psychic force isn't just mindless energy waiting to be harnessed. Psychic force is the psychic energy of a higher realm of consciousness. What psychics perceive as a psychic force is usually just the leg of an elephant - it's hard to see the whole thing from below.
Being aggressive is generally a useful attribute for a psychic, but being greedy or recklessly ambitious is not. A psychic approaches a psychic force with inner purity and careful balance.
If you stare at the sun too long, you'd better be sure of what you are doing!