I use my bathroom basin and shower , while showering. Also my kitchen sink , for dancing in before breakfast!!
I do side bends plus twists round etc. and plies on my toes facing front. (holding on to the basin!!) Pulling in my stomach. all the time. I walk on my tiptoes with straight legs and pulled in belly when I remember and I lie flat on my bed and do sit ups!! Much cheaper than buying all those exercise machine or joining a gym I couldn't be bothered to go to!!!.