I barely had the money for it but I joined a gym and got a personal trainer. Having someone to report to really helped me change my diet (especially since the first one I had and I became good friends). Top diet advice: Eat breakfast including protein, replace soda for water, drink over 1L of water per day no matter how many extra trips to the bathroom you will have to make, and have about 5-6 small meals per day.

The other reason why I paid for a personal trainer was because I have no idea how to use weight lifting equipment or what kind of exercises to do and doing it wrong would make me even more prone to back injuries.