Derr... I was waiting for a thread like this to show up sooner or later, and at this stage in my life my answer can either be very short, or very, very drawn out. For here, I'll keep it short.
Nothing in our everyday lives has value unless we give it such. The material things you love, the work you do, your hobbies, your life legacy - none of this means anything when the only definite things in our lives are that we're born and later, die. What matters are the thoughts and feeling we personally put into them (for example, one's person choice to relax at home watching TV all day holds no less value than someone who spends their day working outdoors. Ignoring the health-related benefits, there is no invisible scale of 'value' that exists for entertainment-based activities. All that matters is that both people enjoy what they're doing). Also, yes, I do believe in God, and I do believe in concepts of 'fate' and 'destiny'. I probably don't, however, believe in these concepts the same way the average person would. When it comes to a 'purpose of existence' that we ourselves can comprehend, it all comes down to the trials/experiences we face and lessons we learn along the way. Through these experiences, we all come to discover our own purpose for existence.
I'm honestly not a follower of existentialism concepts, I just came to these thoughts/conclusions on my own and later on realized that they closely match parts of that philosophy. That said, just because I view nothing as having inherent value, that doesn't mean I'm a crazed bastard who believes nothing I do matters. I try (yet don't always succeed) to treat others and nature the way I'd want to be treated - free of needless pain and suffering/destruction, because reality throws enough of it our way to begin with.
And I'll leave it at that.