You may recognise the title, “Footprints in the sand”, it is based on the well-known story of a person looking back on their life as footprints in sand. For most of the life, there are two sets of prints, one of God, and the other being theirs. During the hard times of their life, there is only one set of footprints, and so the person accuses God of abadoning them in times of difficulties. God replies that he didn't leave them, but instead, carried them through the difficult times.
Leona sings that she promises to carry someone special through their difficult times when their heart is full of sadness, and you'll find her footprints in the sand. The thought of the petite size 10 Leona Lewis carrying someone is something I'd like to see!