'The Bachelor' Matt James said he drinks protein shakes and lifts weights to marathon prep after gaining 20 pounds over the holidays

• Matt James, star of "The Bachelor" season 25 is training for the upcoming Boston Marathon.
• His new routine includes protein shakes, weight lifting, and a strict schedule.

Former football player and star of "The Bachelor" Matt James said a routine of lifting weights and eating protein is helping him get in shape after a relaxing holiday season.

Between running the New York Marathon in November and prepping for the upcoming Boston Marathon in April, James said he put on weight with some holiday indulgences, but he's back to training hard.

"I gained 20 pounds, so I definitely enjoyed myself during the holidays. To get back into the right mindset, I think it is important to develop a strict regimen and hold yourself accountable," James told Insider in an interview coordinated by his partnership with sports nutrition company Dymatize.

Prioritizing protein, keeping healthy habits, and hitting the weight room helped him re-commit to his fitness goals, he said.

Stop overthinking and just get started

Whether you're a gym newbie or coming back after time off, procrastination can be a major challenge to starting an exercise routine, according to James.

Rather than letting details delay your workouts, build motivation and momentum by jumping into any form of exercise, even if you start small.

"Just take that first step and go to the gym. I think people can second guess themselves because they don't feel prepared, but if you try your best everything will fall into place," he said.

James said asking a fit friend to recommend a gym or trainer, or even join you in a workout session can help you overcome 'gymtimidation' and fitness anxiety.

Make a plan and stick to it

James said his marathon training involves a strict diet and exercise routine and hitting his goals early in the day is key.

"For me, it starts with my morning routine. If I miss a workout or start my diet off on the wrong foot, I am more liable to get pizza for lunch, and then I am right back at square one," James said.

While one pizza, indulgent meal, or missed workout is unlikely to make or break your goals, it can be a problem if it escalates into repeatedly derailing healthy habits, experts previously told Insider.

Get enough protein

To keep his body in peak shape during training, James said he prioritizes protein, a macronutrient essential for rebuilding muscle tissue and maintaining a healthy weight.

"When you're running over 50 miles a week, your recovery plan is just as important as the run itself. So, every single morning I like to stretch, stay hydrated, and make sure I'm consuming enough protein."

His go-to shake includes chocolate Dymatize ISO100 Whey Protein, strawberries and bananas, nut butter, and almond milk.

Lift weights, even if you're a runner

In addition to putting in miles, lifting weights is an important part of marathon training for James.

"I didn't lift enough before the New York Marathon, so whenever I am not running, I like to isolate a muscle group and stretch after a heavy lift," James said.

Strength training can help runners prevent injury, improve speed and endurance, and build explosive power.

Experts say weights and cardio complement each other, so you don't have to choose between them. Certain styles of weight training, such as high-volume workouts, AMRAPs, or supersets, can even improve your cardio, no extra running required.