Sincere effort.

“Go to your room and shut the door – make no fuss. Sit down and talk to God. Practice meditation. Let your mind become so intense that the next time you sit to meditate you won’t have to make the effort; your mind will be fixed immediately on Him. If you don’t make a great effort to conquer physical and mental restlessness in the beginning, you will have difficulty every time you meditate throughout the years. But if you make that supreme effort at the start, you will soon be happy and free.”

– Sri Sri Paramahansa Yogananda
Book – Man’s Eternal Quest
Chapter – “Making Religion Scientific”, page 52