"how do you stay motivated?"
It's not always easy but here are some tips :

Create your personal "reasons list." Keep a piece of paper and pen handy for a couple of days. Jot down EVERY reason you can think of that you want to get healthy/get fit/lose weight through consistent exercise.

Real life example: I spoke to a lady a couple of months ago who could only think of two reasons that she wanted to lose weight and get fit. I told her to think about it for a couple of days and she came up with a list of over 30 reasons, such as:
more energy to spend quality time with her family at night

to be able to fit into all the clothes in her closet

to be able to live a long, healthy life and to enjoy time with her children, husband, and grandchildren (eventually)

to not be uncomfortable in public

to not become breathless climbing stairs

to be able to do "active" things with her family and friends

to be able to play on the floor with her children

to be able to wear nice clothes

Her list goes on, but you get the picture. Make a long, extensive list. This may not seem important, but it is critical to be able to read this list when your motivation to exercise is waning. It's a powerful way to quickly get "re-motivated"!