Once in a physical body, Spirit Guides are masters at helping you achieve your life goals. Keeping in mind that you really are the creator of your universe, Spirit Guides try to steer you toward your original goal that was originated prior to your physical birth. There are always bumps and hurdles to overcome in any lifetime, but those are usually put there because of your actions and may or may not indicate additional karma. Your spirit guides help you to overcome this or succeed in completing the karma from past actions, words, or deeds.
Different belief systems believe that we have anywhere from 1 to 5 or even more Guides upon physical birth. And then there are also Spirit Guides that help you temporarily to succeed in learning a specific goal or task, who then leave once the task is completed.