He landed awkwardly when falling from Tapaculo at Newbury on Saturday and does not intend to resume race-riding until Thursday at the earliest.
Now the second most successful rider in National Hunt history, he won last year’s Gold Cup on Native River, who will attempt to defend the title on Friday week.
Johnson, who received his OBE from the Queen, was speaking as he prepares to mark the 20th anniversary of his first Festival win when Anzum – trained by the late David Nicholson – made up dramatic late ground to win the Stayers’ Hurdle in 1999.
“It was frustrating. Tapaculo was beaten at the time when he unseated me and even though it didn’t look that bad I landed awkwardly,” said Johnson, 41.
“It’s not always the worst fall in the world, it’s how you land. I was badly bruised at the bottom of my back and it hurt a lot. Sometimes it disappears after five minutes, but it didn’t.
“Thankfully it’s temporary rather than anything major. I saw the physio on Monday morning and she’s happy that the bones are as they should be.
“I just need to try to rest a bit and give it some time.
“I’m fine sitting up or walking, it’s just the bending, which I obviously have to do when I’m on a horse.
“I’ll go swimming. It’s a good way to do some exercise without impacting my body.
“Pilates has been very helpful for me over the past few years, it keeps you supple and strengthens up your body.”
While his Gold Cup wins on Looks Like Trouble (2000) and Native River 12 months ago remain the pinnacle of his career, Annzum’s unexpected success two decades ago kickstarted the jockey’s career that has seen him accrue over 3,500 winners.
“I was second on him in the race the year before and until then I hadn’t ridden any Cheltenham Festival winners, but I had quite a few seconds in the couple of years before that and it was starting to get quite frustrating,” he recalled.
“I thought I had a chance of being placed on Anzum before the race, but there was Le Coudray, Lady Rebecca and Deano’s Beeno also in the race and they were the big three, with Le Coudray being the banker from Ireland. I really was only hopeful over anything else.”
Anzum often required plenty of assistance in the saddle given his lazy style of racing, and Johnson conjured the best out of him.
After touching down in fourth over the final flight the pair powered up the run-in to defeat Le Coudray by a neck.
“We were flat out from the moment we jumped off, but I knew if we kept in touch and that if I kept pushing he would stay on well,” he recalled.
“Even coming down the hill I thought I might only be placed and even jumping the last, although it is a long time ago, I was pretty sure I didn’t think I would win as we were only fourth going over it.
“I noticed the first two (Le Coudray and Lady Rebecca) were stopping in front and he just powered up the hill. He was a fantastic little horse. I remember schooling him as a juvenile, so I knew lots about him. He was never a speed machine, but he was a stout stayer and had always been a good horse.”
Not only was the victory a landmark moment in Johnson’s career, but it was the final success at the Festival for Nicholson who had mentored the then promising rider.
He said: “When the ‘Duke’ left the stands he didn’t realise he had won. He thought he had run really well to be second, then someone said ‘congratulations’ and he was a bit shocked.
“It was not very often the ‘Duke’ was shocked. To have my first Festival winner for him was a big thing as it would turn out to be his last winner at the meeting. It meant the world as he was the man who gave me my opportunity. Aboard Anzum it was a bit of a blur, so since then I’ve made sure I appreciate every winner there, as you never know if it will be your last.”