It's impossible to have a totally perfect and joyful life constantly, There will be ups and downs in life obviously. Though you can try to have a consistently happy life by following certain rules,by having good moral conscience, try to prevent making bad decisions, Etc. etc. etc.
Don't fear what will come. If something happens it happens. Remember there are things you have to face in life. Drama will always lead to bigger issue. If you wanna be happy work on you and find out what you wanna do. Don't be a follower