Bhagavad Gita Verse 9, Chapter 14

sattvam sukham sanjayati rajaha karmani bhaarata |
jnyaanamaavritya tu tamaha pramaade sanjayatyuta || 9 ||
 
Sattva binds through joy, rajas through action, O Bhaarata, while tamas cloaks knowledge and binds through heedlessness.
 
sattvam : sattva
sukham : joy
sanjayati : binds
rajaha : rajas
karmani : action
bhaarata : O Bhaarata
jnyaanam : knowledge
aavritya : cloaks
tu : while
tamaha : tamas
pramaade : heedlessness
sanjayati : binds
uta : and
 
Shri Krishna recaps the characteristics of the three gunaas in this shloka. Sattva binds by making us hold on to joy experienced after attaining a sense object. Rajas binds us by giving us joy in performing actions and obtaining their results. Tamas binds us by giving us joy in holding on to laziness and heedlessness. We now begin to look into how these three are interrelated.
 
In the second chapter, we have come across a series of shlokas that describe how the mind can fall from sattva into rajas and tamas in a matter of seconds. We start with the mind resting in a peaceful sattvic state. A tinge of rajas comes in, causing us to think about some sense object, let's say a sweet. This fuels rajas further, creating a strong attachment to that sweet, culminating in a strong desire to do anything to get that sweet. But it gets worse. If we cannot get that sweet, if someone or something obstructs our consumption of the sweet, anger arises in us. Rajas deteriorates into tamas. The last rung of the ladder of fall is when anger goes to such an extent that it causes us to lose our faculty of intelligence and memory.
 
Conversely, we can go from tamas to rajas to sattva, but it may take a little longer. For someone steeped in tamas, immersing themself in action will raise them to the level of rajas. When action becomes focused and directed towards the pursuit of a selfless goal, rajas is elevated to the level of sattva. Swami Vivekananda always used to say "awake, arise, stop not till the goal is reached". When India was under British rule, many had become accustomed to this slavery and had fallen into a tamasic state. They could not find a way out of their predicament, and were clouded in ignorance. Swami Vivekananda's message urged citizens to engage in action towards independence. That was the only way to get them out of the tamasic state of laziness.