The most beloved fasting to Allah is fasting alternate days. The Prophet ﷺ told ʿAbdullāh ibn ʿAmr: “Fast a day and break a day; that is the fasting of Dāwūd, and it is the best fasting.” When he wished for more, he said: “There is nothing better than that.” (al-Bukhārī & Muslim).
العربية: عن عبد الله بن عمرو رضي الله عنهما أنّ رسول الله ﷺ قال: «صُم يومًا وأفطر يومًا، فذلك صيام داود عليه السلام، وهو أفضل الصيام». (البخاري ومسلم).
For those able, fast every other day — the fast of Prophet Dāwūd, most beloved to Allah.