Real power is to be able to make decision purely based on what makes you happy.
Hopefully helping others makes you happier than doing something selfish.
And if that's the case it would be selfish of you to help others - and with that being said go ahead and be selfish.
In the end it's all about you. Whatever you trying to do with your life is your decision.
Selfishness is not living as one wishes to live,
it is asking others to live as one wishes to live.
Don't want that boring job with a good salary? No problem! Not interested in going to the gym? Totally fine.
If your goals mean something to you they will always be at the center of attention. Take a break - go travel, meet new faces, get inspired. Do whatever makes you happy. Happiness is the only currency – and power is making a decision with that in mind.