That's a fantastic goal! You can totally do it!!
There is a quote that I absolutely LOVE, it goes; "A year from now you will wish you had started today."
I hope you keep it in mind as you go on your journey. It will totally get hard, but just do your best and keep at it.
I will also suggest to join some challenges (there was a challenge that started on Oct. 1 to loose 30 pounds in 3 months, and another challenge - Halloween challenge - had just finished... So keep your eyes out for those). There are also exercise challenages that you can easily join late (you set your own targets, even if it's walking for 30 minutes a day, it's whatever you decide, and there's one that just started "Nov/Dec/Jan 90 day exercise challenge"). There are daily weigh in threads, etc. Just have a look through and see what fits.
If and when you do hit a rough patch, I would also suggest to really lean on the community here. We all have those moments when we start heading in the wrong direction and that's when a lot of people stop participating, but the truth is that no one judges here (we ALL get it), so if you do begin to question your motivation, post here and people will respond and stick with you!!
My "name" here, is 1yr2mkovr for precisely the same reason! I'm giving myelf a year to get myself back on track! Good Luck to you!!! I wish you a great journey!!