Generally in Western culture when we refer to someone having a ‘heavy heart’ we are speaking of someone dealing with grief or deep sadness. The Lord has a different perspective.
2 Every way of a man is right in his own eyes, But the LORD weighs the hearts. Proverbs 21:2 (NKJV)
When He speaks of weighing the heart the Lord is examining our motivations. From His perspective a heavy heart is one that carries His presence.
In the New Testament Paul said his afflictions were working in his life the eternal weight of glory (2 Corinthians 4:16-18). Paul was a Hebrew and a former Pharisee. His comment on the ‘weight of glory’ is a reference to the Hebrew word kabod, which literally means ‘heavy’ but is used it in a figurative sense to mean glory, honour or splendour. The reason Paul spoke of the weight is twofold, one is that the primary meaning of kabod is heavy or weighty. The other is that we can see the tangible result of the weight of His presence in the lives of believers.
The context for Paul talking about the weight of glory is our transformation into the image of Jesus.
18 But we all, with unveiled face, beholding as in a mirror the glory of the Lord, are being transformed into the same image from glory to glory, just as by the Spirit of the Lord. 2 Corinthians 3:18 (NKJV)
As Christians we carry His presence. When we respond correctly to whatever is happening in our lives the ‘weight of glory,’ His presence, increases in us. I am sure all or most of us have met someone in whom we see Jesus. Those are people that from His perspective have a ‘heavy heart.’ They get that way by how they respond to circumstances. When Paul talked about beholding Jesus I believe He referred to sitting with and before Him, fixing the gaze of our heart upon Him. I also believe, based on what he wrote in chapter four of his afflictions and what they were working in him, that another aspect of beholding Jesus and being changed is seeing Him in whatever we are going through and looking for His presence there.
So what is the Lord looking for when He weighs our hearts? He is looking for Jesus. Are we also looking for Jesus in our circumstances no matter what they are and thus carrying and releasing Jesus splendour, glory and character wherever we go?