When I lost over 100 lbs the first time, I went by increments of 10 lbs. I didn't look at it as 100 lbs, but as 10 lbs. After the 10 lbs down, I started my next set of 10 lbs.
It took away the overwhelming thought of , WOW, 100 lbs I need to lose and made it more mentally manageable. Next thing you know, it's only a total of 50 lbs you will have to lose. What an incredible feeling!!!

My other motivator was taking a pair of pants/shirt and using that as my gage of weight loss. I would keep putting the same pants and shirt on and then when that was to overly large to use as a gage, I would get something smaller and so on. Sometimes a scale can discourage a person.

Hang in there, I am in your boat too!