God is the source of our strength, our rock, and our salvation. 
We can do all things when we stay in connection to Him.

Philippians 4:13 says,
"I can do all things through Christ who gives me strength".

John 15:5 says,
"I am the vine; you are the branches. If you remain in me and I in you, you will bear much fruit; apart from me you can do nothing".

We aren't much without Jesus, and we can't do anything purposeful without Him. It's important that we make time in our schedule and room in our hearts for Him at all times in order to stay fruitful and productive in our lives.