It's not tough if you follow these steps:

1. Choose the right supervisor to guide you in PhD research. If you mess with this step, then be prepared to live a miserable life.

2. Choose field and research that you are really interested in. It's hard to stay motivated if you choose the research you are not interested because PhD requires you to read heavy research papers and write critically.

3. Manage your time well. Set up goals every time you need to finish the tasks.

These steps are not necessarily right to all people. Some of them (maybe a few) finish their PhD successfully without following these. Perhaps they are lucky or gifted. But following these steps will make your life easier on the road to obtain your PhD.