It's easy to lose motivation. When this happens, I fall into the trap of setting a 'restart' time to chase that goal. But what usually happens is I will give myself excuses to push back the 'restart' time. This happens over and over again.
What works best for me is to start what you have been putting off NOW! Don't look for excuses to start later (especially true if you are like me who will find more excuses down the road). I hope my experience will help some of you.