Im 27 years old i get tired very quickly even if i run for 5 minutes or jus a simple walk.what will be the reasons behind that and how to overcome.

Checkup for reason: Unusual complaint unless you have been bedridden or suffer from a chronic illness. Doctor need give you a physical looking for an underlying disease. If none found need to walk a 5 minute walk every other day and increase the time every week by 10%. Eventually get up to 2025 minutes then start substituting a jog for portions of the walk. If walking ids too much you start with stationary cycling.