'Charity, regarded in itself, does not become charity until it comes into act and becomes work. For to love anyone, and not to do good when we have the power, is not to love them. But to do them good when we have the power, and to do it from our hearts, this is to love them.' (Arcana Caelestia 6073.1)
Loving others is doing them good from our hearts 'when we have the power.'
When do we 'have the power' to do that one more service for another? When do we have the power to take on one more job? When do we have the power to push harder in our efforts to deny Self?
What lies within our power? This is something that each of us must decide. Only we can set the borders of our limitations. Only we can push those borders back, in order to accomplish more, or to change our state.
Deciding how much power we have to love and to do – how able we are – is a matter of judgment and wisdom. We can accomplish very little good by taking on what we (or our loved ones) cannot handle. All our 'uses' are then compromised. And so, we all must set priorities and respect each other's decisions regarding them.
Yet it remains true that our power to do anything depends greatly on what we actually do. Doing is what increases our capacity to do. Doing is what increases our capacity to will and love. One might suppose that simply willing and loving increases our capacity to will and to love; but this is not so, unless one does what one wills and loves.
'Unless a person does what they will, there is within them a failure to will, which eventually becomes a want of will.' (Divine Providence 151)
It is in doing – in exerting energy, in actually expressing our good will, in taking the time to move our body and mind for a purpose – that we experience the full sense of empowerment, and the full joy of loving. As the Lord said:
'If you know these things, happy are you if you do them.' (John 13:17)