For a couple months now I have not been able to properly run, especially uphills, because of the pain in left butt and the back of the upper thigh. My osteopath suggested it is an issue of difference in the range of movement in left and right hip joint (I can certainly feel that the left one is stiffer), so that the muscle needs to do the work of the joint. The pain started when sitting for longer periods of time, but first did not bother in any other ways or times. Then we were running some speed intervals on the track, when I suddenly started to feel pain in the left hamstring, and then some more, and then I had to stop.
View from La Bastille this morning.

So for about two months now, I have been riding my bicycle, a couple of times outdoors, but mostly in our living room and recently on the balcony. But even more I have been climbing stairs to La Bastille hill — for some reason that movement does not hurt as much as walking or running uphill — and running down. We have not counted all the steps, but there are two consecutive stairways with 8×11+5 and 28×11+5 steps, which make a little over 400 steps. These remarkable stairs are also mentioned on the Wikipedia article of Bastille fortress. Altogether there must be about 600 steps on the way to the very top, from about 200 meters to 476 meters above sea level, and they take us about 30 minutes to climb (an update — there must be at least 1000 steps, since Tomi counted the last section, with 170 meters to go to the top, and it had 162 steps).
Doing that four to five times a week has done miracles to my aerobic shape, which was not that bad to start with. By the end of the Summer, and particularly UT4M mountain marathon in August (with total climb of 2500 meters in about 40 kilometers) I can probably run all the way up without being out of breath.
La Bastille hill after our run this morning.
View from our balcony to the neighboring daycare center. There are so many fresh shades of green around at the moment.
Another view from the baclony and more shades of green.