Welcome to middle age. It really is a wake-up call for many.
Just keep riding some, it will come back to you... or not.
At almost 70yo, cycling is more important now than ever to me. But I don't ride faster or further. Saddle time with smiles over miles. Take some pics, entertain us. Ever pack a proper lunch for a longer ride?
You sound the competitive type - try the indoor smart trainers. Group rides and races, virtually all over the World. Less hassle, no roadside break-downs, etc.
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Vintage, modern, e-road. It is a big cycling universe.