Once, an invader on horseback from Central Asia had occupied Delhi and wanted to have a victory procession. An elephant was decorated and upon mounting it, he asked for the reins of the elephant. When told that it is controlled by a mahout, he jumped down and summoned his horse, saying that he never rides on something whose reins are not in his hands.
Similarly, we need to introspect as to whether we hold the reins to our happiness and emotions or someone else. All of us think that we hold these reins, but the reality is that the reins are often with someone else. It could be a friend, someone in the family or workplace whose moods, words, opinions, praise and criticism make us happy or unhappy; a thing like food, drink or physical possession; a favorable or unfavorable situation; even our past or future.
In this regard, Krishna says that he's a yogi who, at any time before liberation from the body, is able to master every impulse of lust (kaam) and anger (krodh). He is a happy human (5.23). Kaam is nothing but getting happiness from others and krodh is what happens to us when something doesn't go our way.
Krishna further says that he who is happy within, who enjoys within, who is illumined by the inner light, such yogis are united with the Lord and are liberated from material existence (5.24). With sins obliterated, doubts removed, senses subjugated, the sages, contributing to the welfare of mankind, attain the bliss of brahman (absolute) (5.25).
Service is about attaining awareness about self along with compassion towards others. Krishna indicates that one can help others once he knows how to help himself by mastering impulses of lust and anger but not by someone who is already a slave to them.
Source - Daily World