1) My friends/relatives are coming to stay with me. I won't have time.2) I have a baby to look after.
3) I will be out of the town.
4) I cannot bear the pain.
5) I have a flu.
6) Yoga is against my religion.
7) How much will you pay me for a lesson?
8) You can go to Geylang and look for a prostitute. Give her money and she will follow you to do all poses.
....and endless list of excuses.
Number 8 is the most creative excuse. :)