My wife was low-carb last year when my step-daughter was diagnosed with Celiac disease.  That made the house gluten-free and for the most part started me down a low-carb diet change.  My wife & I gravitated to a Paleo/Ancestral "diet", which became a lifestyle.   We also started working out with weights, then moved to Kettlebells (namely the Skogg System) and more recently the TRX suspension training as well.

We do do "cheats" on occasion,   and it is remarkable what havoc the 'carbage' (mostly grains) wreaks on our systems for the next few days.   For me this is not an 'end'  but more of a beginning, or at least a stop along the way.

CHALLENGES: 
giving up Pizza, Bagels, Pasta and Beer

ADVICE: 
Just TRY It!   even if for only 2 or 3 weeks,   you WILL feel a difference.   

I was a shocking 360 pounds, I had diverticulitis, knee pains, and was constantly low energy with poor sleeping habits and bad health.  I also had some nervous ticks like hitting my legs just above the knee for whatever reason (I'm thinking leaky gut).  

After shifting to a paleo diet (yes, I go off the rails about once a month) it's just gone.  I'm now down to 255, I sleep well, I lift weights and exercise, I no longer have knee pain or neurological oddities.  I am less anxious, and my diverticulitis is gone.  My knee pain vanished and now I have a standing desk. I'm migrating into doing a lot of personal training and paleo guidance on the side and a lot of my friends and family have seen a huge improvement as well.  

CHALLENGES: 
The biggest challenge is finding time to think ahead about meals, and learning to eat on the fly when you can't do that. It takes a while to learn where you can and cannot easily eat and to learn to choose foods that are good for you. 

ADVICE: 
Do not let perfection stand in your way.  If you can only get cheap cuts of supermarket meats and frozen veggies then do that.  If you can't live without a diet soda in the morning then go nuts.  Taking that first big step away from gluten and tons of sugar is the best thing you can do for yourself and even if you're diet isn't "paleo perfect" you are doing better than 95% of the people out there eating a SAD.