Can you minimise the number of things that require your distraction each day? If so, you might still be able to make progress against your main project, although not as quickly as you would like. Try to cycle through your distractions back to your main task several times a day. Aim to increase the time on your main task and reduce the time on the others with each week.

If it is multiple ideas/projects that are keeping you from focusing on one, then maybe you have to accept that the only way to make progress is to work on all in parallel. Be warned this will likely increase project completion time an order of magnitude, and you run the danger that nothing is finished in the end.