Noun
strength of will (uncountable)
The ability to stick to one's prior commitments, strivings, etc.; determination, willpower.
F'lar recognizes that Lessa possesses both unusually strong psychic abilities and great strength of will. Source: Internet
She saw it her duty to compensate for the innumerable deficiencies of her strange husband through her own intelligence and strength of will. Source: Internet
The strength in Dreamwalking depends mostly on the person's strength of will and imagination. Source: Internet