How you do those runs? You put your stopwatch at 30’ and record the distance you’ll make?
You need to follow some kind of structured training in order to achieve that. If you want to do it relatively easy, you should do strides for a long period of time, say 6 months, then try again.
”You run comfortably fast for 150 -200m then walking or slow jogging 100m and on again” Repeat x 30. After 6 months (probably quite less than that) you’ll achieve a PB!
Check this post and video. Also the video(s) below.
Thanks for the advice.
Regarding my running, it tends to be determined by how much time I have available when I take a break from working from home (25-30 minutes tends to be the usual) and the good old-fashioned “how I feel on the day”. The latter is probably the reason I ran 11.2 km in 50 minutes last year. I felt good and, like Forrest Gump, I kept on running.