What often helps my analysis paralysis is to focus on the first step, for example: I've decided to go for a bike ride but it feels overwhelming because I'm not sure which route to take, instead of stressing over the route (which can take hours as I go through different options and how I feel about them etc and eventually stop me from going) I set a goal to go downstairs to the garage where I keep my bike. At that point I already have my cycling gear on and it's much easier to hop on the saddle and take some direction without thinking about the route so much as I'm already on the move.
So my advice: try setting an easier goal. Think about the first step you can take. For example instead of thinking about doing a full workout decide to just go and see the gym. Now that you are already there you may feel like you want to do some exercise as well.