To echo what wcsjms said above, it very much depends on whether you are used to hiking hilly terrain.
I live near the top of a steep hill in England, and didn't really find the climb to Orisson overly strenuous (and I was 58 at the time). I found the actual distance harder.
In March this year I was walking from Astorga to Sarria, and met several people who had walked the Valcarlos route from SJPdP (the Napoleon route being closed). Without exception, they all said how hard they had found it; it is not a flat route - there is a rather steep climb after Valcarlos which takes you to Roncesvalles. It doesn't sound as though taking the Valcarlos route is really very much easier.
But from my perspective, crossing the Pyrenees (with an overnight at Orisson) was a fantastic experience, and an incredibly empowering one. Now, whenever I encounter a problem, whether at home or work, I just give myself a mental kick, and say something like 'come on, deal with this - you've crossed mountains, this is nothing compared to that' and I love that it works for me.
You've got this. You can do whatever you want, but it will be good whichever route you choose. Buen Camino my dear x