Marisa: I just completed the Camino in May of this year. We started in Valcarlos, which is about 3km from the French border. All-in-all, we covered 521 miles. While no picture of perfect health, I found the road to be quite challenging, and not for a "beginner".
We started with three guys in our group (all in our thirties), and one of the men bowed out about 2/3 of the way there. We had some rough weather to start (we rode in May and had rain the first three days), and things seemed steeper than the maps we had would've led us to believe. We always thought that for every uphill there was an equal and opposite downhill. That wasn't always the case.
I recommend that you consider it seriously before going the "full length". In order to get the Compostela for having completed the trek, you must ride the final 200 km (100 km for walkers). That's still 120 miles, and no leisure ride. Galicia is very hilly, even if you stick to the automobile road and off the pilgrim's footpath. We didn't see a single pilgrim in two weeks that was under the age of 18 (or at least looked under 18), and we saw nobody on their bikes that looked younger than we are.
That having been said, after having completed the pilgrimage road, I would
never discourage another would-be pilgrim from making their own pilgrimage. The road is full of history, culture, and a unique spiritual feel, regardless of the faith you profess. Take the challenge, but make sure it's the right time in your life to undertake such a feat. Buen camino!
P.S. You can read my pilgrim's diary at
this site which has graciously been provided for me by MadridMan!