Are there any eye exercises to develop eye focusing?

Not really. There are a number of (frequently expensive) programs which promise correction of vision by various forms of eye exercise and manipulation. These do not work but will be quite successful at ridding you of your cash. LASIK surgery is so successful that you really should discuss that if you want to get rid of your lack of focus.
Eye exercises. Eye exercises are typically not useful for eye development once the patient is older than 10-12 years old. One exception is patients that develop issues with near focus and pencil pushups (focusing on a pencil being moved from distance to near while maintaining focus over and over).