Time travel has been invented and it goes like this.
You travel backwards in time at the same speed you normally travel forward. Everything is identical - you do all the actions the same but in reverse. When you return to the present you live your life at normal speed just as you did the first time.
So what is different? Well only your consciousness is travelling the timeline. Although your body is locked into all the old actions, your consciousness can form new memories as it moves backwards and forwards.
Suppose I go back to when I was 8 years old. I can relive the exact same experiences as I had then, first backwards and then forwards. I will see the same things and experience the same things but in reverse and then at normal speed forwards.
If I want to go back a year then it will take me a whole year to get there. Then I will need another year to return to the present. For this reason people tend to go back only a short time - for example to find the wallet they lost earlier in the day. With luck they can observe themselves losing the wallet but of course they can't do anything about it. However at least they know precisely where and when it happened and this will help them find it. They might even be able to see themselves being pick-pocketed and mentally take note of the thief's appearance.
You can only wind backwards and forwards like a movie and cannot change anything that happened to you and therefore there are no paradoxes. Or are there?
Has this solved the time-travel paradox or can you find some fault in the scheme? What could go wrong?
You cannot change the past. You just watch history unfold as a spectator locked in your own body. You experience everything in perfect, exquisite detail just as you did the first time around. (Thanks to Caio Nogueira for asking)
Travel in either direction occurs at the same speed that we already travel forward in time.
There is no way to fast-rewind or fast-forward.
You can of course travel forwards in time but only at the normal pace! In other words nothing is different from normal living. Only reverse time-travel makes a difference.
You must set the time in advance so, once you have set off, there is no way to change your mind.
Time travel is available to most people.
Edit: Imagine that your body is a four-dimensional object. It exists at every point in time simultaneously. Therefore none of your actions can ever change. It is only your consciousness that can move back-and-forth along the timeline.
It seems that there are lots of paradoxes and/or impossibilities. Therefore I believe my question has been answered.
I shall however leave it open because I need to go through everything and see if I can find a new method that avoids all these problems. Thanks to everyone who has answered or is still going to answer. Eventually I will try to choose the 'best' answer.