A wearable infusion device for delivering medication into body of a user, the infusion device comprising a medication container containing a volume of medication to be dispensed; an infusion needle that is fully enclosed in a sterile environment until the infusion needle is inserted into underlying tissue; an infusion needle insertion mechanism associated with the infusion needle, powered by one or more mechanical springs, that when activated, inserts the infusion needle through the skin into underlying tissue; means for delivering medication out of the medication container and into underlying tissue via the infusion needle; and a housing associated with the medication container, the infusion needle, the infusion needle insertion mechanism and the means for delivering medication.