Forget everyone around you and decide why are you doing it? What are you working towards? Who are you trying to please?
The answer to each question should be "YOU".
You are doing it for you, you are working towards a better you and the only person you should be trying to please is you!
We get so caught up watching the people around us when in actual fact whatever they are doing, whatever they are working towards - it is irrelevant.
And there is absolutely no need to give a crap about what they think of you. We are each working towards something individual, be it weight loss, muscle gains, marathons, strength, lifestyle changes...
How you get there is up to you - the journey you take to reaching your goals is entirely down to your determination, perseverance and self belief.
Just because your friends have fallen off the wagon doesn't mean you have to and equally just because one friend might have reached their goal in X amount of time doesn't matter either. It's your journey, it's your body, your mind and your life.
So quit worrying about if are still doing press ups on your knees or if occasionally you have one cheat meal too many. If YOU want it, you will get there.
Use the support systems around you but don't rely on them. Turn setbacks into experience, make notes of your successes and acknowledge when you know you could have tried harder.
Don't beat yourself up if you haven't reached your goals by the desired date. Without sounding too cliché (but I will) it's not the just end result that's important - it's how you got there. And if you can say hand on your heart that it was YOU that got you there, then there is no better feeling!
Remember that feeling, let it spur you on. Use the the negative and the positive to make you a stronger person.