Two common misconceptions about motivation are:
1) You should feel highly motivated all the time
2) You need motivation to do a job / task / workout / chore
There is quite a lot of information and theory behind motivation but for the purposes of keeping this post simple and useable for you:
1) Motivation ebbs and flows - Think of the seaside, you have periods of high tide and periods of low tide. Your motivation is the same - it comes and goes - so you will have periods of high motivation and periods of low motivation
This is perfectly normal for everyone.
The key is understanding this and realising you won't feel motivated all the time and that you still need to work towards your goals.
2) Try starting the job / task / chore / workout first - Linked to the above point, you will have periods where you're not motivated to do something and you don't want to start.
However, work on putting that feeling aside and starting the thing you need to do - whether it is a job; a task or a workout.
Give it about 5 - 10 minute of getting into the work and often times, you'll feel more motivated and then want to get it finished.
After it is done, give yourself praise for the completion despite not necessarily feeling like it.
This is my, mostly, Personal Trainer musings and information which I hope you'll find helpful!