Devout Jews had very strict rules about having a day of rest on the Sabbath (Saturday). They mistakenly believed the rule was there to make people miserable. It was actually meant to be a gift from God that gave people guilt-free rest. Also note that when Jesus calls his disciples, he prays first.
Prayer before making a key decision is modeled for us by Jesus. It is so important to bring God into the decision-making process, not for God to agree with us, but for us to agree with God.