Tips for days noted "strenuous" on Ireland tour

At the Giants' Causeway, there is a visitor shuttle bus that will run people up and down the hill from the visitor's center to the causeway. It is a nominal cost and will save a great deal of wear and tear if you need it.

I took this tour in 2018. I am in my 70s and have a wonky knee. I did just fine with using my walking sticks on uneven surfaces. For instance, the walk up the grassy hill to Dun Aengus was a time when I was so glad I brought them along. I loved the Giant's Causeway because they have a shuttle bus down to the pillars. I do remember another place I used the sticks was The Burren because of the rugged surface. I skipped the fort in Kinsale because they were hiking back to town. Bottom line, prepare, bring a cane or sticks, and if you aren't sure you will be comfortable going on the planned excursion just let your buddy and your tour guide know.

You can do it just take your time. The bus at causeway is great well worth it only euro or so. Cliffs can be seen walking a slight graded path and stop where you want. Do not have to go up to the lookout to get a good view. I have mobility issues with Fractured back and was able to do both using a cane. Enjoy!

If you have survived 5 RS Tours that had strenuous days, then you'll have a good idea of what you're in for. I honestly don't recall that any of the tour days listed as strenuous were actually strenuous, except for the free day in Dingle when I did a hike of my own choosing. As has been noted you can opt out if necessary, just talk to the guide. If you have hiking sticks those will help with uneven ground (even in Dublin the cobblestones can get you). Worst case you can find a pub and have a chat with a local :)

Your primary concern will be some of the uneven surfaces you'll encounter.
For example, the walk down to the Giant's Causeway isn't particularly challenging - it's a fairly gentle slope - but the terrain is somewhat uneven and the stones themselves once at the bottom might pose a particular test of your balance ... especially if wet and slippery.
A good pair of walking sticks would help you quite a bit I think.

I did this tour last year and didn't find it especially strenuous. Yes, the Shepherds' Steps at the Giant's Causeway are pretty rough -- we took them down, I wouldn't have wanted to take them up -- but they're optional. You can either walk on a gentler path or take the shuttle as others have described. It's not hard to walk to the edge of the Cliffs of Moher on a paved path, and you don't have to climb much to get great views. (In fact, the views of the cliffs themselves are closer to the parking lot than the broader, but less interesting, views from the highest cliffs out over the ocean. As for the Charles Fort, on my tour the bus returned some of us to town and others chose to walk back with the guide. I spent the extra time on a boat tour of the harbor.

If you're walking four miles a day you're doing much more to prepare than I ever did, and I'm in my late 70s. Can't speak to your sciatica flareups, though -- no one on this forum can. It would be a shame to miss this tour just because a flareup could occur. Keep in mind that you can skip any activity away from the bus if necessary, with notice to the tour leader and your buddy. And there's a lot to see and do that isn't strenuous at all.