The inability to learn something new is a part of inner laziness. Mind is leaking its energy with all its worry and anxiety. If one does not put the wise effort to stop it, then it shows there is inner laziness. Most of us are tired more from mental worry than physical work. When one learns to be happy there is overflowing energy which gives delight rather than leakage. Whenever you overflow, you share and expand. When there is leakage of psychological energy you shrink and struggle to survive.
Oh, Mind Relax !
People spend 'half their waking hours daydreaming'
(Read the foot note - the yoga perspective on scattered minds)