Find some time to read these books. Your mental state after reading them is a good way to judge whether a career in science is your cup of tea.
1. The Origin of Species by Charles Darwin: Theodore Dobzhansky once remarked that nothing in biology makes sense except in the light of evolution – this is not an overstatement. Wading through pages written in dense Victorian English won’t be easy (some of Darwin’s ideas were later shown to be wrong). Those who persist will find themselves rewarded with a sense of deep appreciation for how evolutionary thinking has changed the way biology is done, and the way we view our position in the tree of life.
2. Advice for a Young Investigator by Santiago Ramon y Cajal: The author is a Spanish Nobel Prize Winner in the beginning of the 20th century. An excellent teacher and an outstanding experimentalist, Ramon y Cajal cared deeply about the youth of his nation, and wrote this book to exhort them to achieve greatness, reminding them that with the correct work ethics, it is possible to produce important work for humanity in face of adversity (Spain was a declining power at that time). Although written close to 100 years ago, much of his advice is still relevant today. Interestingly, there is a section on how to choose a spouse that is compatible with a science career!
3. How to Solve It by George Polya: I didn’t like math in high school. But reading Polya (a great mathematician and teacher) in university changed me completely. If you suffer from math phobia, then this book will likely cure you. Polya guides you in thinking mathematically, boosting your confidence in solving math problems. Strongly recommended for lifting morale.