Metacognition, often described as “thinking about thinking” (Schraw et al., 2006), plays a pivotal role in effective learning. It encompasses the awareness and control individuals possess over their own cognitive processes, significantly impacting their ability to acquire, retain, and apply knowledge. This chapter will explore the key facets of the metacognitive side of learning, focusing on Self-Regulation, Metacognitive Awareness, Rumination, and Procrastination, and then discuss how engagement in lifelong learning can foster metacognitive development. In what follows, each of these constructs is briefly introduced, followed by the more comprehensive exploration of each.