Bhagavatham gives a wonderful answer here. The decisive factors that should determine your actions are explained. Whatever you do, should be appropriate to the time of action, the place where it happens, suitable for your health, relevant for the situation and supported by your wealth.

Whenever you have a doubt, please keep this in your mind, analyze and take a decision.

Surrendering your Karma to the Lord is explained very simply here. When you say that the Lord must be pleased, it implies that the Lord who is present in the benefactor and the beneficiary as well, is pleased.

It makes you perform your duty with an unbiased mind, free from all worries and anxieties. Such a peaceful mind alone can work creatively and enthusiastically. Then, a positive result is guaranteed. This is the secret of success in any field.

The simile given between the Sun and the king is heavily loaded with meaning. This is the true potentiality of a dispassionate mind.  Whatever you do, you can enjoy it without your mind getting glued to it or stuck up in it.