For years (and I mean years) I tried to develop a stretching routine but could never make it stick. As an athlete, I could not understand how I could tolerate so much pain and suffering on the tennis court since I was about 10 years old (I’m 36 now) — going hours and hours and hours on end — but could establish a habit of stretching for 15 minutes, let alone 5 minutes every day.
Over the decades, I would every so often feel inspired and try and stretch my hamstrings with the good old fashion “bend over and reach for your toes.” I would try this during a hot shower, a way to loosen up my muscles first and temporarily increase the range of motion. Then I would grit down on my teeth and reach as far as I could for as long as possible. Long story short, this maladaptive behavior never stuck; how could it? I was constantly suffering and this is no way to establish a stretching routine.
In any case, that’s enough backstory (for now) and here are some resources I recommend
Stretch Therapy (ST) Starter Course
Check out this beginner’s course if you are new to stretching (or if you are like me, athletic but stiff as fuck)