Recommended fasts include Mondays and Thursdays, the three 'white days' of each lunar month, six days of Shawwal, the Day of Arafah for non-pilgrims, and the Day of Ashura. The Prophet ﷺ observed and encouraged these.
References
Sahih Muslim 1162
Informational, not a personal fatwa. Consult a qualified scholar for rulings on your situation.