Yes, svadharma is important as you need a field of activity, a vocation or profession that is in line with your most powerful desire. It is easier to be happy and excel in your svadharma. This is chosen by looking very carefully at what inspired or excited you from childhood onwards. What did you visualise yourself as when you were a child? Not passing fancies, but deep-rooted life interests. What were you always attracted to?
Give it thought over a period of time, starting afresh every time. Then you will get a shortlist of two or three fields. Select the most powerful among them. But this is only the beginning. In that field fix a higher goal, a nobler ideal, not just for your own benefit. The higher the goal, the greater will be your enthusiasm and energy. However, it is not that suddenly life will be enjoyable all the way.
Even if you have identified your svadharma correctly every day will not be exciting or thrilling. In the beginning, life will be tough, perhaps boring. You must use your intellect to stay with it. The intellect will keep you steady. Then you will not change and shift as per your moods. Using and developing the intellect is most important in life.
If you have made a mistake and chosen the wrong field you can change if you are convinced that it is not your field but do it after careful analysis and understanding. Do not make impulsive decisions based on temporary, passing fancies.