Undoubtedly true is the Tao-, Stoic-, Gautama etc. principle that says that ALL ideation is SOLELY in one's own Mind. The two entities (Tao: That and This, Stoics: That what is, and That what is not in one's control, Others: The Outside and Inside etc. etc. ) are of utmost importance when realising that one's happiness, happens in one's mind, is therefore ONLY controllable by one's own Mind. By using one's body and knowledge, one may be able to alter things in the outside, so that the BODY can be more comfortable. Epictetus: 'Where things are not dependent on choice, be courageous; where they are, be cautious'. Is it possible to be happy under torture? Answer: Yes. Epictetus: 'I do not say you may not groan, but do not groan inwardly ...'.
With regard to death. There is no evidence, nor a likelihood, of Mind going on after death, indeed, death IS absence of Mind. To live with the aim of a happiness in after-life, is a self-inflicted insanity, leads to irrational behaviour, misery but is easy to cure by (self-)changing one's ideas.
With regard to goal in life. Life has but ONE goal: Life itself, Ego, 'I' (Cicero, Good Life) Live, therefore, with the object to prolong and maintain Ego, in harmony with Nature, be well, think well, learn and teach. It is impossible to live in order to achieve this goal for other(s). Therefore, try not. But take into account, our, (human) extra capacity over animals. This enables 'feeling-with', or sympathy. It is well nigh impossible therefore, to be happy when observing or even causing unhappiness in others, even in animals (Rousseau: not let children observe cruelty in animals (Emile )). But with regard to 'socio', it is thus that the fundamental interests of each practically always clash with each other, but, also, in a socio each participant depends on each other's co-operation. Ratio, Ideation (3 rd degree) can overcome the animal (harmony) of jungle law, by Order, Organisation, and self-discipline. But, ... when the other is jungle law, then you must also be jungle law.