Having little butterflies is ok but being tremendously nervous means you are afraid of losing your money and you will certainly lose your money. You see what you believe and bring it to fruition. If you believe you'll fail, you have already failed. Fear and greed are the core reasons Traders make or lose money.
The way to eliminate this nervousness or fear is to use an efficient money management system and specific stops before you initiate any trade, no matter what market. Let's assume, you have $25,000 to trade Forex, commodities, Stocks or whatever. For Forex or commodities, I'll use 10% or $2,500 to trade. If I am very experienced, I'll use 20% or $5,000. You now have $2,500 or $5,000 as actual trading fund leaving a cushion of $22,500 or $20,000 respectively for volatility, depending on your experience. You now use precise stops to protect the $2,500 or $5,000 trading fund. For example, if you have your stops at $900 (for the $2,500) and $1,250 (for the $5,000), once your stop is hit, you close your positions immediately and take your loss. You can always reenter the market if it goes back to the previous direction you anticipated. If not, change direction and follow the market. The market is king and you don't fight it. That will be suicidal. It's easier said than done.
Now, you already know how much you are ready to lose if the market goes against you, $900 or $1,250. Be ready to lose that money and acknowledge that you made a mistake and then do the right thing. This should eliminate your fear because you have already taken into consideration the worst case scenario and how much you are ready to lose.
Always analyze your worst case scenario and be ready for such eventuality to eliminate your fear. As long as you are using effective stops to protect your self, you should not operate with fear, which is very destructive to trading. It can paralyze you from taking action. Trade with fun and calm neutrality and you will make a lot of money.