Fate is normally understood as a certain course of happenings. Destiny is the culmination of the results as a consequence of these happenings. There can be various approaches and theories as to these two terms. But in essence, in common understanding, fate is inevitable and the destiny falls upon the person according to the developments depending upon the fate of the person.
When things are favourable to us, we do not think about these terms. The ponderings start when things are unfavourable. We start looking for answers and even blame God as to why He is doing this for us. We go to astrologers, do different kinds of rituals, particular type of worship to please different deities, go for pilgrimage, visit important places of worship etc. During the course of these events, if things turn favourable we feel that God has listened to our prayers. Otherwise, we feel God has been so ungrateful to us. This is normal human psychology.
Now, does God play any role in setting our fate and destiny? I do not think so. We are all part and parcel of That Supreme, no doubt. We have also acquired, from That Source, our sense organs to live in this world in this human body. While our Source remains constant, unchanged, ever in bliss (as we call the Soul or Atman), with our sense organs and our mind, we do lots of activities during our life journey. We have full freedom to do what we want. But the ownership of those actions squarely lies with us and thus the consequences also have to be faced on the basis of the result of those actions. Freedom goes with accountability and responsibility. And no one can deny this fact.
So, where do fate and destiny come into play? They are as a result of continuous actions and consequences in the journey of life. If we channelize our efforts keeping That Source in mind and do our actions, beneficial to all living beings(which are also from That Source), the outcome will be favourable. If we accumulate all consequences of our wrong actions out of our ignorance, the outcome will be unfavourable. As I said, the freedom is with a tag: accept it with responsibility and accountability. This is the Law of Nature.
Therefore, our scriptures always advocated humility, surrender, love, piousness, and total devotion to That Source. They do not deal with fate and destiny in the sense we understand them. These concepts must have originated much later. There is nothing as a separate hell or heaven independent of the consequences of our actions. Everything is here, right in our life cycles. The message is, do everything keeping That Source in mind and be one with him so that the cycle of births and deaths culminates in merging with That Source.