If you are a bit unfit then you may find it tough. I personally don't like the hills at all these days,
but I can do it in spite of an occasional bad back and sciatica.
All due respect to Gwen (Holistica), but if you live there and do it Daily - you get very acclimatised to it, plus Gwen is quite fit anyway.
(yes Gwen - you are one fit lady - LOL)
I on the other hand am getting older now and I also get a touch of Asthma, but the hill was manageable.
We stayed in the Moros Apts. just 20 metres down the hill from Tsaras and I found it a bit tough going, but everyone seems to make it OK.
I hated the hill when the sun was Hot, but in the evenings it was not so bad.
My advice is go slowly, stop for a short rest halfway up - turn admire the view, and you will be fine.
Tsaras has a nice pool and bar to stay in if you don't like the walk to the beach, and a nice restaurant is just below you - Elphita Bistro.
When we stayed there a few years back, we were getting quite used to it by the end of 2 weeks, and it seemed a shorter trip then somehow, by the end of the fortnight.