How to keep them motivated with no cost and waste of time?

• Make a stand up meeting every morning were team embers will update each other on their progress and development, will share problems and will ask for solutions. This meeting should be short and people must stay stand for better mobilization and energizer. Keep everything simple; set a standard for the presentations – for example 2 min each. It gives a very good boost for the day.
• Introduce Office Olympics were funny competitions will relief the stress. Think about games that will suit every member of the team and try to make everyone involved. Few ideas here and here
• Office quizzes- include information about the team members, hobbies, funny situations.
• Build traditions in the team – Wednesday snack out or Friday burger in the office, or poker night once a month.
• Sometimes piece of paper and couple of markers can make miracles. Ask your team during meetings to draw their vision for the company and how to improve the working process.
• Be creative.

For more team building exercises see here