We all want peace; no war, peace without sickness, and just peace of mind. If you want to be filled with fear, just turn on the negative-filled news. It is easy for fear to set in with all the negativity around us; fear of war, fear of the economy, fear of sickness, fear of loss of job, fear of crime, fear of rejection, fear of the unknown. All of these can rob us of peace of mind.
If people and circumstances do not rob you of peace, then Satan is quite busy hoping to steal what is left of your inner joy.