Each of us have tasks to master on our path. I have repeatedly stepped out of my comfort zone throughout my life to pursue what I felt I was called to. It's apparent you have been called to teach & The Universe still has plans for you in that capacity. I agree - retirement isn't for everyone. But for me it has been the opposite of what all the nay sayers told me to expect. I am far from rich - my pension is less than 1/2 of last salary. But I'm happier and less stressed. For some of us that's our path. And just as you said in this piece - we know it by the sounds of our footfalls & the echoes we leave in our wake.
When the winds of change blow for you - as they always do - you will know where to put your next footfall. Just keep listening to your heart. <3