Lifting weights is taxing on the body and some of the bigger lifts like the squat and deadlift require a certain amount of flexibility for you to become proficient in the lift.
Limited movement resulting from tight muscles or poor flexibility will limit your ability to perform at your peak.
To overcome this use mobility exercises as a way to improve your flexibility and range of movement. Foam rolling, hip rotations, ankle stretching and banded shoulder stretches are all simple and easy ways to achieve this.

Improved mobility will assist you in gaining strength, which will, in turn, assist in you to getting leaner and developing a much better physique.
Make improving your mobility a priority.
A good physiotherapist can aid you with this and should be able to write you a program that works with your weight program giving you the best results possible.

Contact for further tips on improving your fitness.