The Couch to 5K concept — gradually building from walking to running a 5-kilometre race in eight weeks — has helped millions of people become runners. The key insight is that the barrier is psychological more than physical: most reasonably healthy adults can run 5K if they progress gradually enough to avoid injury and discouragement.
Week by week approach
The classic structure alternates running and walking in each session, three times a week. Week 1: alternate 60 seconds of running with 90 seconds of walking, for 20 minutes. Each week, increase the running intervals and decrease the walking until, by week 8, you are running continuously for 30 minutes (roughly 5K at a comfortable pace).
The gear that matters
Running shoes matter enormously for injury prevention. Visit a specialist running shop for a gait analysis — they will watch you run and recommend shoes that suit your foot strike. Everything else is secondary. Cheap sports clothes work fine; expensive GPS watches are enjoyable but entirely optional.
The mindset
Running slowly is still running. The objective in the early weeks is to finish each session, not to be fast. Most beginners run too fast and tire out within two minutes, then conclude that they "can't run." Slow down until you can hold a conversation while jogging. That is the correct pace. Progress, not perfection, is what gets you to 5K.