By the experience of active love. Strive to love your neighbour actively and indefatigably. In as far as you advance in love you will grow surer of the reality of God and of the immortality of your soul. If you attain to perfect self-forgetfulness in the love of your neighbour, then you will believe without doubt, and no doubt can possibly enter your soul. This has been tried. This is certain.
I love you, and because I love you I believe in you. But if I did not believe, still should I love. Had you come back for me, and had there been no other way, I would have gone into the jungle with you - forever.
The day that a woman who is passing before you sheds a light upon you as she goes, you are lost, you love. You have then but one thing to do: to think of her so earnestly that she will be compelled to think of you.
First become alone. First start enjoying yourself. First love yourself. First become so authentically happy that if nobody comes it doesn't matter; you are full, overflowing. If nobody knocks at your door it is perfectly okay; you are not missing. You are not waiting for someone to come and knock at the door. You are at home. If somebody comes: good-beautiful. If nobody comes that too is beautiful and good.
That is the most common excuse, and the most foolish of all. Love has never prevented a man from following his dreams. If she truly loves you, she will want the best for you.