I feel like I miss someone who I don't know

 I can't explain it, but lately I feel a mixture of intense contentment and intense loneliness. I walk outside and feel the sun on my skin, the way it gently kisses my cheeks and I smile. I feel free. But then I feel this intense sadness. Like there's something vital missing. From the situation. From the heart. It feels like I miss someone who I don't know. What am I missing? Is it because of my old friends? My old life? My future life which I haven't grown into? My family? The love I have never experienced with a partner? The freedom of travelling? I wish more than anything I felt free but this society constantly moves so fast it does not give us time to breathe. To think. To feel. What should I do.. how can I take a step forward when I feel like I'm tied down to the past.