If you feel overwhelmed, it's important not to forget that:
1. those actions were there the day before you started gtd, they all represent some form of engagement you allready had. The only difference is that now they are in one place together.
2. you don't have to do those 150 next actions right now, not even this week. I'm a self employed consultant and typically, I have around 300 next actions on my list at any moment. It just means I have a lot of projects going on at the same time. A lot of them are small, some are bigger. At the weekly review I tag about 70 of them to work on the next week.
Some would then put those 230 other ones on their some day/maybe list (bacause not planning on working on them the coming week). I don't, because I like having them around, in case I can do something to make them move forward (depending on context, if I have to print something out, I might have a look at the list to see whether there is some other printing job there, even if it's not tagged for this week, this allows me to move forward on some projects way before the deadline is there). But that's up to you. If your actions stress you out, make sure you only see those that you want to work on during the upcoming week.
3. go back and re-read number 1
Myriam