Often God's timing and ours differ. We may expect that our mission work will be completed in a short time, whereas the actual time can be far longer.
Mission work is often difficult and can take many years. It can take years to learn a culture and another language. And it often takes many years to build life-changing relationships that bear fruit.
Are you committed to God's work for the long haul?
With SIM (and many other missions) you can go to the mission field for as long as you want. SIM classifies people who serve for more than 2 years as 'Long-Term' missionaries and as such, you become full members of the mission.