The answer's fairly simple.
You need a boss.
There's not something wrong with you. On the contrary you're like 80-85% of the population who are unable to work without a boss. Most need fear as a motivator. Fear of losing their job.
When you're working for yourself you don't have that fear once you've made enough to eat and pay the basic bills, which you say you have. Making money above and beyond the basic needs isn't fear-motivated, so you need to find something else within.
The solution is:
Get a boss
or
Become a boss
A boss doesn't care about money, so you can't be a boss by wanting money. People that want money are people who don't have money and people who don't have money don't have it because they don't have the right mentality, the boss mindset.
A boss wants to build something, be a leader, build an empire. The motivation you'll get from wanting to build something is 10x stronger than the motivation you'll get from wanting money.
Look at athletes.. The ones who reach world and olympic level don't do it because they want to "look good". They do it because they want to reach their absolute maximum human potential, then go even further and they want to do it for their country. THAT is why they can train 8 hours a day and push through excruciating pain.
People who want to look good won't have that motivation. Once they hit some pain they'll push a bit, but it's not a strong motivator.
You need to ask yourself what it is you want from life and find that thing you really want. Once you find it you won't have motivation problems. Money is *NOT* it. For *ANYONE*. Money only makes achieving your dreams easier and more fun, but money is NOT the dream.
It sounds to me like you're suffering from depression, man. Doing stuff like exercising and changing up your diet can help, as can getting involved in some kind of new and exciting project or hobby. A lot of the time the problem is that all your days are exactly the same, and you have nothing specific to work towards. Maybe a new hobby? If you can afford it it never hurts to talk to a psychologist or psychiatrist. If you're facing a real chemical imbalance in the brain, medication is an option.
lol, he's not suffering from depression. Being frustrated because you've not made millions yet is hardly clinical depression! 95% of this forum are frustrated at their income.