Kristin Cavallari finds being a mother ''scary''.

The former 'Hills' star and fiance Jay Cutler became parents for the first time to son Camden Jack six weeks ago and though the 25-year-old beauty is loving the new chapter in her life, she admits to feeling apprehensive about having so much responsibility.

She said: ''I like having this life that I'm responsible for. It's exciting and so rewarding but it's also a little scary!''

Kristin admits she changed completely as soon as she held her son for the first time.

She told the new issue of PEOPLE magazine: ''It was the most incredible moment I've ever felt. With Camden, I've realised what really matters. We're a family.''

Meanwhile, Chicago Bears player Jay, 29, is already seeing signs that his little boy could follow in his sporting footsteps.

Kristin said: ''He pointed out right away how big his feet are! And his hands were massive - he'll sure be able to hold a football.''

The reality TV star got engaged to Jay in November 2011 for the second time.

The pair previously called off their engagement in July 2011, just three months after they had originally announced their plans to wed.