Here is a great article that tells you how you can use your unique talents to create happiness in your day to day life. The problem with smart people is that they are oversensitive. They tend to focus too much on what they lack thereby becoming unhappy. The article gives a great solution to this problem. Most smart people are talented in multiple things. They can focus on those talents and use them in an appropriate scenario. It is proved time and again that using your skills appropriately puts you in a blissful state.
If you are brave, seek a new adventure like caving or whitewater rafting.
If you are a leader, volunteer to head up a new project or social committee.
If you are a learner, read a book about a new topic, take an online class, or join one at your local community center.
Some other things I can think of:
If you are a good sportsman, take out 15 minutes every day to practice with someone who is your level or up.
If you are a good writer but if your job does not include writing, try and write up some answers on Quora.
All the best in becoming happy.