Hello Popi
I know whats it like to feel like you want to give up on something you are doing , but you need to remember that this something that you are doing is so you can become the best version of yourself and be the best kind of you there is. Every time you feel like giving up and not doing something , tell yourself that if you dont start now , then you will never start. Remember that you are doing this so you can become a beautiful , strong confident you! Which is something we all need to be . Try to listen to music that motivates you and keeps you excited and going, keep track of your accomplishments and the days you DO do something good for yourself dont let those days go to waste and appreciate yourself everyday you do do something. You could also reward yourself every time you exercise everyday for a week , or for so many days continuously. Also like Inky said you could pay for it and remind yourself that you HAVE to go because you did pay for it! Always keep an image of yourself and what you WOULD be like if you did exercise daily , remember everyday and every action counts!
Good luck