The idea of "fantastic voyagers" carrying out medical tasks within the human body has existed as part of popular culture for many decades. The concept revolved around a miniaturized robot that can travel inside the human body and perform complicated functions such as surgery, navigation of otherwise inaccessible biological environments, and delivery of therapeutics. Since the last decade, significant developments have occurred in this arena that are yet to enter mainstream biomedical practises. Here, we define the challenges to make this fiction into reality. We begin by chalking the journey from pills, nanoparticles, and then to micro-nanomotors. The review describes the principles, physicochemical contexts, and advantages that micro-nanomotors provide. The article then describes micro-nanomotors' obstacles such as maneuverability, in vivo imaging, toxicity, and biodistribution. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.