Supposedly saudade is a (Portuguese) word to that describes a feeling of simultaneous sadness and happiness. It is the recollection of feelings, experiences, places, or events that once brought excitement, pleasure, and well-being, which now trigger the senses and make one experience the pain of separation from those joyous sensations. However it acknowledges that to long for the past would detract from the excitement you feel towards the future.
I feel like in our culture we have tendency to categorize emotions into being either good or bad. Happiness, excitement, love are good emotions, while sadness, boredom, anger are bad. Those categorizations aren’t universal though, and saudade is a perfect example of how that can be. I can feel sadness for the loss of a person or the memory of a time and place, but still be accepting of where I am in the present and have excitement for the future. I can miss a person while still being happy for them without regret. We need more words like saudade in the English language.