I started on C25K and after a few injuries and illnesses I've been relatively healthy for at least two years and find that perseverance has paid off. I'm now running ParkRun each Saturday (or volunteering) and find that I can't get faster than 32 minutes.
So ... I've taken up an online Runner's World 6 week programme to increase my speed. runnersworld.com/uk/trainin... I'm aiming to get under 30 minutes.
My point is that I'm persevering. I'm neither fast nor slow but I'm now in a regular running routine each week which brings a satisfaction of its own. In fact, it has now given determination to lose some of those persistent Kgs that have been hard to lose, despite the running. That might even help to lower my times.
So, my revelation is that perseverance is everything. Stick at it, build confidence and self-esteem and take on new goals. 'Inch by inch, row by row.'