Deciding on an activity after a setback--need advice

This is a long question: sorry. I had a TAH with removal of both tubes, both ovaries, and the appendix on March 26 and had been doing well, but last weekend I spread mulch (not a lot) and walked a lot of stairs at a wildlife refuge; this week I've had a lot of discomfort and "swelly belly." My scar is particularly tender, for some reason.

I'm a community college teacher, so my summer schedule is flexible (designing two new courses for fall and learning the college's new web page program). I actually taught four classes from home during my recovery time, missing only a week when I didn't have the energy to sit up and Skype. Recovery had seemed uncomplicated.

Here is my issue. I am giving a talk at a conference next week--the group is my favorite professional organization, so I'm going, even if I end up slipping out of some sessions to rest in my room. This event will have me away from home from May 28-June 2 and involve air travel, bus rides, and sitting around in airports (luckily, for relatively short periods). I am then scheduled to drive five hours on June 8 (no other way to get where I'm supposed to go from here) and spend eight days evaluating essays. There is no flexibility in that schedule; the days start at 7:30 and run until 5:00with occasional stretch breaks and an hour for lunch, but no time to get back to the hotel for a lie-down until the end of the day (and I am still feeling the need to "stretch-out" my incision, if that makes any sense).

The eight-day gig pays well (more than I make teaching a summer class, which is why I do it), but the money isn't strictly necessary: it goes into the saving-for-a-vacation fund. (Yes, I'm incredibly lucky.) My worry is that the intensity of the week will set me back, as just last weekend's brief overdoing did. If I'm going to cancel, I need to do it now so that the organization can replace me; waiting to see how I feel on June 2 would put lots of people in a bind.

Does anyone out there have any advice for how long it takes someone in her late 50s to get over a setback?

Only you know how you feel, but I will suggest a few things.
Ask if there is a restroom or area with a sofa at the essay part. Usually conference centers and universities, etc will have a couch or such to stretch on during everyones fifteen minute break. Take a comfortable pillow for sitting on. Take the most comfortable clothes you can. Take motrin on schedule the whole time.

He speaking engagement prior to this, plan to do little sitting in and only your speaking session. Add on as you see fit.

Hugs. If you are worried, cancel. However, since it seems to be lifting and stairs that irritated you,it may be fine. Just be sure to ask someone to lift your suitcase when needed and have a rolling one.