It is not that God is watching us sometimes, He is watching us all the time. Bring this thought into your conscious awareness. At present we have the awareness of "I am" but we escape the thought of "God and Guru are with me". We need to practice thinking "God is with me". As a result, our mind will be attached to God-Guru while we do our daily chores and we will automatically start offering our works to Him. This is the state of Karmyoga.