As a professional of over 14 years, Defoe knows a lot can change in football in 12 months.
This time last season Defoe was on top of the world. The striker had scored twice for England in three appearances and he had nailed down a first-team place at Spurs, where he found the net three times in his opening four matches.
Now the picture is quite different. The 30-year-old is yet to start a Barclays Premier League game and he did not feature against Moldova and Ukraine despite the absences of Wayne Rooney, Daniel Sturridge and Andy Carroll.
Defoe is desperate to make the cut for what would be his last World Cup, but the Tottenham forward knows his chances of making the plane to Rio - should England qualify - are not being helped by his lack of first-team action.
"It's important for me to play this year," the striker told Press Association Sport at a fundraising gala dinner for the Jermain Defoe Foundation.
"I want to play games because it's a World Cup year.
"Having gone to a World Cup, it's something you want to experience again as a player.
"It's the best thing ever, representing the country when the whole world is watching, so I understand the importance of actually playing in a World Cup year."
Roberto Soldado has repaid a chunk of his £26million transfer fee by scoring four goals in his first five games since moving from Valencia.
Consequently, Defoe's Premier League game time this term consists of seven minutes at Crystal Palace, nine against Swansea and a 21-minute cameo in the north London derby.
The fact that Defoe cut short his summer holidays to spend two weeks in France with fitness guru Tiberius Darau only heightens his disappointment at not playing regularly.
"It's frustrating when you have worked really hard in pre-season," he said.
"A boxer trains for eight weeks before a fight and then on fight night he wants to be ready and perform, but he actually wants take part.
"I went away, worked hard and made sure I was fit. I felt sharp and stronger than ever so it's difficult when you are in and out of the team."
Gareth Bale's annoyance at the slow pace of transfer negotiations with Real Madrid led him to skip training last month.
But with this being his ninth season at Spurs, Defoe's love for the club means he will not let his frustration get the better of him.
"It's important for me to stay cool and keep focused," Defoe added.
"When players go mad they take their eye off the ball and it's difficult to come back from that because when you are angry you can't perform.
"There have been times when I have been angry and you are in training and you don't feel great, but at the same time it's important for me to keep sharp because if someone gets injured then you are in, so you have to be ready."
The fact that Defoe still has a chart up in the gym that tracks his climb up the Spurs' top scorers' list - he is now sixth - suggests his love for the club still remains strong.
Another topic close to his heart is the Jermain Defoe Foundation, which he set up in the summer.
The foundation is aiming to raise money to build a new children's home in St Lucia, where his mother Sandra is from.
St Lucia was devastated by Hurricane Tomas in 2010, which claimed the lives of 14 people on the Caribbean island.
"That was the spark that made me decide I wanted to set up the foundation," Defoe said.
"It's my second home there. All the kids had their education taken away from them and they are still suffering. Hopefully we can raise some money and change their lives."