Sattva binds one by comfort and happiness, rajas by activity, O Bhārata. Covering knowledge, tamas binds one by carelessness or inattention.
Existence and expression, to be complete and vibrant, need to be complex. That is how the three gunas are there as an inspiring and mutually balancing combination. Due to sattva-guna, one is able to gain happiness, delight, which all relish. But existence will not be full and desirable, if not accompanied by the other two gunas.
Thus rajas has the effect of engaging one in activity, by which the energy provided by food and nourishment is utilized and exhausted. Activity is indispensable for anything to exist. Rajas produces desires in the mind and impels one to act to fulfil the desires.
Equally so is tamo-guna’s role. Ignorance caused by tamo-guna provides the possibility and need to learn and gain knowledge. Imagine how many branches of knowledge and research we have! How desirable it is to strive for knowledge and grow! Similarly, how important is sleep to become active again!