NLP books help. Try introduction to NLP. Anyway, for me when I'm feeling down or not as active I do the following:
1. workout( will add energy and positive outlook during the day)
2. listen or watch inspirational stuff ( ask your self first, what are things that inspire me? People who inspire me? .. Everyone is different in this case)
3. Appreciate everything you do. Instead of seeing everything as negative look at the good things in everything instead. Enjoy your food, weather, health, friends, and basically everything that is happening around you. ( won't be easy at the start, but you can master this if you try it few times)
4. How do you like to feel? Act the same way! Acting and feeling the way you want is crucial too. Can't go into details right now as im in hurry
5. Finally, I take half an hour a day to sit myself and think about anything that happened that day. It makes me feel better in most cases. Don't sit by your self for a long time or you will get depressed .
That's all I can think of right now..

discipline is how you solve this problem,

start with small menial tasks, add them to your day, also remove tasks from your day that are part of a regular routine that you don't wish to continue but are in the bad habit of doing, train yourself to be emotionally strong when it comes to forming new habits and removing old ones

the feeling won't change, but eventually you will develop a stronger sense of discipline and just do the things you don't want to do, because you realize they are important to you, as you previously commited yourself to doing them, follow through with your plans again and again

going to the gym is one of those things, you don't work an 8 hour shift on little to no sleep, get home, and say, yep... this seems like the perfect time to go bust my ass at the gym for 2 hours, fuck no, your brain is telling you, rest man just relax, you just worked 8 hours why go to the gym when you can sit down?, just learn to tell your brain to stfu and go to the gym every day like clockwerk no excuses

it also helps if you start to excersise the ability to do things in the present instead of saying, yah, ill totally wake up and go to the gym tommorow, start focusing on what you can do from moment to moment, what can you do right now?, not in the future, why wait?, that report from work is due in a two days, do it now, you need to get your ass in shape, go to the gym now, you want to go sarging at some point this week, do it now, don't wait for later, later never comes, things only happen right now

Yeah I get you, I used to do the thing where you write down what you want to do the next day on a sheet of paper... It worked for like 2 weeks but then it got so boring with all the repetition and shit I just sacked it all :/

that is the point of starting with really small tasks at first, so you get used to the idea of changing the habits without having to invest too much of your own energy into the process, gradually increasing the difficulty level of the new habits, it takes somewhere around 70-100 days for a new daily routine to become solidified as a habit, a strong sense of discipline is required for those 70-100 days, but take it one day at a time, and once you pass the pain period, it will feel normal

before you know it, you will have the self control to make and break habits as you choose