As mentioned in Bhagavad Gita that we should follow our own Swadharma rather than copying others but how to know our own Swadharma? One might say that it is the activity without which you tend to be restless but isn't it against the very essence of peace and stability? If you say that we should follow our interests then would not it be an attachment towards a material thing? I feel like I should be a polymath then would it be called a swadharma as it is just multidisciplinary in nature? If yes then how should I pursue it according to Bhagavad Gita or any other scripture?
Svadharma means whatever is in tune with our nature.
One's own duty, even if without excellence (i.e. inferior in the scale of worldly values) is more meritorious spiritually than the apparently well-performed duty of another. For no sin is incurred by one doing works ordained according to one's nature.
These verses, which were easy for our ancients to understand, pose great difficulty for us today. So long as Varna was identified with the endogamous caste, and valid texts ascribed particular works to each caste it was easy to find out one's Svadharma, and if one had a will, to perform it too. That a priest's son should be a priest, a soldier's son a soldier, a merchant's son a merchant, an agriculturist's son an agriculturist, a serf's son a serf - is an arrangement that could be practised to some extent in the old feudal society when educational opportunities were restricted, when there was no choice in following professions, when social contacts were limited, and when the validity of the system was accepted by the people in general. But today such an idea of Svadharma hereditarily determined, is impossible of practice. Society and professions have become competitive. The imparting of education without any restriction imposed by caste, has helped the shuffling of professional abilities among all members of society, setting aside hereditary factors. So it has become honorable for any one to follow any profession, and the determination of Svadharma based on birth as in a caste based economy, has become impractical and impossible, and also undesirable. In a democratic society, the same kind of education is open to all, and every one is eligible, according to one's qualification and capacity, to positions of power, prestige and high income. In these days of national armies every able-bodied citizen has the eligibility to be recruited - he may even be conscripted - in the armed forces of the country. In such a milieu, if the Gita idea of Svadharma is accepted as caste based, as it was understood a few generations back, and as it used to be interpreted by old commentators, then it has become thoroughly outmoded and will be rejected by every section of society in India and outside.
But as already pointed out, the wording of the Gita about Caturvarna, except as interpreted by old commentators, does not mean endogamous castes, but the four psychological types. If this is accepted, Svadharma would mean only work that springs out of one's own nature and therefore adapted to one's natural development. But how to recognise these types and how to provide them with work suited to their nature - is a problem that cannot be solved. We have to leave work based on psychological type as an ideal arrangement in a more rationally organised society of the future. There is no other way today but to understand Svadharma as the duty devolving on oneself in society, inclusive of the profession one follows. If that is done well with God in view, and not merely for remuneration or with a worldly master in view, then one may be said to follow Svadharma.
Commentary on Gita 18.47 by Swami Tapasyananda in his English translation of Srimad Bhagavad Gita.