Dear Sir, as I can judge you being in IT industry must be very deficient in sun exposure. You should stand in rising sun with maximum of your body exposed. there is no use of sun exposure with your clothes on. You should also opt for ayurvedic medicine along with it. for it you can consult me on practo paid consult.

The natural source of vitamin D is sun. Ideal is to expose early rays of the sun, like around  8am to 9am.. though vit d is available throughout, other harmful rays like UV are more during peak hours of the day.. early warm rays of sun are the best. Expose skin like extremities, face for about 15 to 20 mins a day, with adequate water intake.