Sometimes God speaks, He nudges, He prods us forward, yet by the time we get going, by the time we respond, it is too late.  This is the way it was with the Shulamite and her beloved in Song of Solomon chapter 5.  While the Shulamite is comfortable in bed, the Beloved knocks on the door and asks for the door to be opened, however the Shulamite is just barely waking up. Her head is spinning as she fights off the desire to linger in sleep, she longs to meet him, but by the time she gets to the door and opens it, the Beloved has left.  The Beloved had come to get the Shulamite for an adventure, but the opportunity had ceased.
Many times in our lives, God nudges us, He prompts, He encourages us to move ahead, yet we are slow in responding.  There may be an adventure ahead of us, yet being slow to respond causes us to miss out.  God may be nudging you to pray, to read His word, to speak to someone, to get up and study, to call a friend, or any other number of things.  Yet we can be too tired, too slow to respond and we miss the opportunity.
Lord Jesus, help us to faithfully respond to You, when You knock on the door of our heart.  Give us strength and ability to respond quickly to the opportunities that You set before us.