I'm thinking of beginning my personal statement nice and early for next cycle and I was wondering how I should explain my poor undergrad grades. Started off low around 2.0 the first year then gradually increased to 3.4, 3.5, 3.9 the past 3 years. Truth is I was immature and not motivated until I was forced to pay for my own school due to financial difficulties in my family. I eventually got a full time job, payed for my school and although it was difficult I feel like I matured a lot. Will it look bad if I cite immaturity as the problem? Or should I try and figure something else to write?
I would address your poor grades and subsequent maturation
only if they are somehow inextricably linked to why medicine is the career for you. For example, you took time away from school to explore medicine further and that experience motivated and re-focused you academically. Your personal statement is your first (and sometimes only) opportunity to explain your passion for this career and to portray yourself beyond your grades, scores, and activities.
Secondary applications and update letters often allow you to address inconsistencies in your record. As does the interview. Further, your strong upward trend speaks for itself. SDN and premeds in general falsely perpetuate the notion that any successful applicant must possess a flawless record, which is far from the truth. Plenty of kids who are accepted have bad semesters, years, etc. It is clear you corrected the problem and demonstrated your ability in and commitment to the classroom.
Moreover, by addressing a weakness, you risk a couple of things. First, you're shining light on a flaw - you're shifting a reviewer's focus from your application in its entirety to a single problem. Do you really want to frame your application in that manner? Second, your explanation of that flaw may not resonate with those who read your application. They may not like or 'buy' your answer or reasoning, which could tip the scales toward an unfavorable decision. Third, you're wasting space provided to you to explain 'why medicine' to address a small issue in the grand scheme of things. A compelling statement of your calling to medicine + an obvious upward trend toward great grades should be more than sufficient.
Use your personal statement space wisely.