Luke 10:40 But Martha was distracted with much serving, and she approached Him and said, "Lord, you do not care that my sister has left me to serve alone? Therefore tell her to help me."
The biggest enemy of focus is obviously distraction - the sun's surface temperature is 24000'F, but unless a magnifying glass is held steadily (not moving around) on one spot, the heat will not start a fire. Martha is a works based performance orientated believer. She thinks God will love her if she engages in much serving. She thinks God doesn't love her or care about all the work she has to do ALONE. She's a martyr, a victim-self-imposed. If people don't help her, she feels abandoned - 'left me.' Martha tries to manipulate Mary to come and help her however Jesus replies that Mary has chosen ONE thing and was focussed on that & He wasn't going to disturb that focus. Give your time, energy, resources to the ONE big thing God has called you to do!