We have a lot of things that we can't do on certain week days. (Tuesday, Thursday, and Saturday).
They include cutting nails, getting a hair cut, shampooing hair etc. Why is it so?
This question has nothing to do with Hindu religion. This is all superstition. Superstition is not religion, nor is it Hindu. This is in not in the Vedas.
Swami Vivekananda said (Complete Works VIII. p 184-187) "We may be under planetary influence but it should not matter much to us. Buddha says 'Those that get a living by calculation of the stars by such art and other lying tricks are to be avoided.'...Let stars come, what harm is there? If a star disturbs my life, it would not be worth a cent. You will find that astrology and all these mystical things are generally signs of a weak mind; therefore as soon as they are becoming prominent in our minds, we should see a physician, take good food, and rest. If you can get an explanation of a phenomenon from within its own nature, it is nonsense to look for an explanation from outside... I lay down as the first essential in all I teach: anything that brings spiritual, mental, or physical weakness, touch it not with the toes of your feet. Religion is the manifestation of the natural strength that is in man...You can swallow the stars by handfuls if you want; such is your real nature. Be strong, get beyond all superstitions, and be free."
I have got a link that consists good reasons:
Since my childhood, I have been hearing from my parents that we should not cut hair or nails on Saturday. You should not shave also on this day. When asked why, they used to tell me that it brings bad luck as it brings anger of Planet Shani (Saturn) upon us. We lose money and peace of mind in our life. This belief is very common amongst Hindus, and hence, most of the Hindus do not cut hair or nails on Saturday.
The answer seems reasonable for those who believe in Astrology and do not like to question the traditions. Those who are not satisfied by the answer always try to find the actual scientific reasons behind such things.
Possible reasons behind not cutting hair on Saturdays:
- It is believed that cutting hair/nail would bring bad luck to the person because it would attract the anger of Planet Shani, which is considered as a deity. In Indian Astrology, Shani has great importance in terms of human life. It is believed that all the bad things that happen to us are because of Planet Shani. Especially, in Kali Yuga, Shani is very powerful and even deities have to suffer from his anger. Hence, it is advisable that one should get his/her hair/nails cut on Saturdays.
- The second most probable and logical reason could be that in old times, the people from barber caste used to do the job of cutting hair and they had no weekly offs. Hence, in that way, they used to get a weekly off on Saturday. Plus, many people in India prefer to cut hair/nails on Sundays. In general, there used to be only one or two barbers in a village. Therefore, on Sunday the workload would be maximum and therefore, they were able to relax and prepare themselves for the rest of the week.
There could be many other reasons behind it. We cannot tell anything certainly today. I have seen many people cutting their hair and/or nails on Saturday and nothing bad happens in their lives. Many businessmen and executives have to shave everyday; still they are earning heavily and living a good life. Problems will always be there in our lives whether you cut your hair on Saturday or not. It is our attitude that matters.
We should remember one that things change with time. This tradition could be right for the old time. There could be some reason behind it but now a day, it seems useless. Hence, we should get off such things from our minds.
Here is the reference link: Why hindus do not cut hairnails on saturdays?
Well, I really do not believe of not doing these activities on certain days. Everything we have heard of to do or not to do on a certain day might be because, so that we do not overdo them. No non-vegetarian food on a Tuesday or a Saturday, some say it is due to Gods special days but he has created equal. Doing things over might hurt us.
Fasting is another activity which I see as a religious thing very similar to above activities. Gods do become happy when we control our senses against some attractions of human-made but the actual reason, we must actually not become their servants.
Cutting hair is said to cause loss of energy. Certain days also put the body into a weak state. Therefore on these day shaving is not recommended, especially for sick or unhealthy people. Shaving at night is forbidden. It is done in the daytime, usually before the noon bath. It should never be done after eating. It is said that shaving on Sundays reduces ones life by one month; shaving on Saturdays reduces ones life by seven months; shaving on Tuesdays reduces ones life by eight months. Shaving on Wednesdays increases ones life by five months; shaving on Mondays increase life by seven months; shaving on Thursdays increases life by ten months; and shaving on Fridays increases life by eleven months. Other authorities say that shaving on Sunday brings physical well-being; shaving on Monday, bright complexion; shaving on Thursday, success; shaving on Friday, universal respect. Shaving on Tuesdays reduces life span; shaving on Saturdays causes decay of the body. Monday is good only during the waxing phase of the moon. However, brahmanas may shave on Sundays and kshatriyas may shave on Tuesdays. Sannyasis customarily shave on purnima. Of the tithis, prathipat, chaturthi, astami, chaturdasi, purnima, amavasya; and sasthis, navamis, dvadasis, sankrantis, and any day of fasting, such as ekadasi, are also unfavorable. The favorable tithis are dvitiya, tritiya, panchami, saptami dasami and trayodasi. The moon in waxing phase is favorable and in the waning phase, particularly the latter half, is unfavorable.
At the least, shaving, hair/nail cut is to be avoided on Tuesdays and Saturdays.