It has been my understanding of "positive polarization" - generally known as "service to others" orientation has its stated "golden mean" to be at least 51% service to others and no more than 49% service to self. For some people, the idea of having two different life purposes might seem somewhat strange, but it does work quite well.
The best way to resolve any conflicts of interest is to find some service to others that is also a service to self in enough ways that it becomes completely self-sustaining.
The danger of doing service to selv and others at the same time is that you can easily lose the balance you need to have by doing something for yourself that is completely self-serving, while not being a detriment or source of friction for others. This can take you into extremely pleasurable things you give yourself permission to do, satisfied that you are well inside the power of giving in balance.
When you start dreaming about what you would really want for yourself, remember to take into considerations your intentions for all your choices. Keep your intentions clear and up front, than the activities you chose will be perfect for you. When it comes to serving others, remember there is an enormous advantage of having people spend their entire lives researching something "far-out" to find a solution after many years and provide many life-times of benefit for humanity. Your shared responsibilities are not to run a meter on your time or effort but your intentions. The rest will take care of itself.