Lately I have been thinking of this and wishing I had worded it differently. I think asking the question "How can I help?" is definitely better. "Can I..." implies there may not be the ability to help. "How can I..." implies not only the assurance of ability, but also the thought that we will not take "no" for answer.
As Christians there needs to be no doubt in our ability because our strength, our ability, is not in ourselves. We trust in His ability to be our strength and our power in and through us. As we pray for others, we also need to echo the voice of the prophet Isaiah:
"Also I heard the voice of the Lord, saying, 'Whom shall I send, and who will go for Us?' Then said I, 'Here am I; send me." (Isaiah 6:8.)
In this life, we are His hands, we are His feet, we are His lips. We give to the Lord the only thing we can, our availability. "How can I help?" should flow off our tongues quickly and easily to those the Lord has placed around us so we can be a light, showing His Light, to our world.
"And He said unto me, 'My grace is sufficient for thee:
for My strength is made perfect in weakness.'
Most gladly therefore will I rather glory in my infirmities,
that the power of Christ may rest upon me."
2 Corinthians 12:8