Jesus had developed the lifestyle of spending time with the Father and communing with Him daily and sometimes He does this on the Mount of Olives. His prayer in the Garden of Gethsemane was not the first prayer and time with God but an everyday lifestyle.
Just before the cross, however, He did not go to the Garden alone but had the disciples following him so they could learn from His practice of devotion. He wanted the disciples to join Him in prayer that they would be strengthened for the task ahead.
When they came to the Garden, Jesus told them to pray so that they do not fall into temptation. Seeing the cross and suffering ahead, Jesus prayed the Father for grace to complete the task; He desired that the will of the Father would be done in His life.
After He had prayed, an angel came to strengthen Him and he was able to pray more. Here, we learn from Christ the need to choose a quiet place for devotion and engage the Lord in prayer. He was receiving strength to endure the pain, shame and sufferings ahead.
In our family devotions, we need to pray the will of God into being than imposing our will on Him. In fact, being committed to time with God as a family strengthens us for the activities of the day and gives us enough strength to go through more easily the challenges and worries of life that hit us each day.